Here is how solved it (feel free to try to solve it first before reading my solution below!):
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1) Look at the first 3 lines and determine the minimum and maximum value for each fruit:
-Pineapple: 0~7.
-Grape: 2~7 (It cannot be lower than 2, because Pineapple + Grape = 9 and we know that Pineapple is 0~7).
-Apple: 0~7.

2) We know Grape is between 2~7, then:
-Max Value (Apple) = 19 - 2x2 = 15
-Min Value (Apple) = 19 - 2x7 = 5

3) We know Apple can't be higher than 7 (because Apple + Pineapple = 7), so:
OK: Apple is between 5 and 7.
OK: Grape is between 2 and 7.

4) We know that Apple + Pineapple = 7 and Apple is between 5 and 7, then:
OK: Pineapple is between 0 and 2.
UPDATE: Grape is 7 (because Grape + Pineapple = 9), since Pineapple is 0~2 and Grape is 2~7.
UPDATE: Apple is 5, since 2x7 (Grape) + Apple = 19
UPDATE: Pineapple is 2. Proof: 7 (Grape) + Pineapple = 9. And 5 (Apple) + Pineapple = 7

---
ANSWER: 7 + 5 + 2 = 14

Three equations, four variables. System is indeterminate. There are infinitely many solutions.

>>936552742
it's 3 variables, double grapes means 2x grape

>>936552863
>four variables
are ya daft anon? grape+grape = 2grape, not a whole ass new variable

>>936551707 (OP)
answer is Friday

>>936552863
>>936553079
I'm retarded and can't count.

Subtracting top from 3rd, you get:
A + P - (P + G) = 7 - 9
A - G = -2

Subtracting that from 2nd, you get:
2G + A - (A - G) = 19 - (-2)
3G = 21
G = 7

The rest is trivial.

>>936551707 (OP)
>Look at the first 3 lines and determine the minimum and maximum value for each fruit:
not necessarily true. Turns out to be true, but I've seen these where the trick is one is a negative number.

>>936553105
we all been there anon. Counting is the hardest problem in math...

>>936551707 (OP)
The answer lies in line 2.

Notice there are 2 clusters of grapes, not 1.

Let's replace this with variables:

p + g = 9

2g + a = 19

a + p = 7

a + g + p = x

>>936551707 (OP)
This can be done by substituting equations and isolating variables. We have:
P + G = 9 <--- Equation 1
2*G + A = 19 <--- Equation 2
A + P = 7 <--- Equation 3
---------------

STEP 1:
Move G to the right:
> P = 9 - G

Replace P with (9 - G):
> 9 - G + A = 7

Move 9 to the right:
> - G + A = 7 - 9
> A - G = -2

STEP 2:
Now we have 2 equations:
> 2G + A = 19 <--- Remember this
> A - G = -2

We can say that:
> A = +G - 2, or simply A = G - 2

Replace 2G + A = 19 with the variable above:
> (2G + G) - 2 = 19
> 3G - 2 = 19
> 3G = 19 + 2
> 3G = 21
> G = 21/3 = 7

Now just replace 7 (grape) in Equation 1 and Equation 3 to get the results for Apple and Pineapple:
> P + G = 9 <--- Equation 1
> P + 7 = 9,
> then P = 2

> 2*G + A = 19 <--- Equation 2
> 2*7 + A = 19,
> then A = 5

G = 7
P = 2
A = 5

>>936551707 (OP)
5 apple
7 grape
2 pineapple

>14, girl, took 8 seconds
>(counted + went back through process, avg 7.1 sec = round down +1 = 8 sec)

>>936551707 (OP)
the correct answer, clearly, is "pen pineapple apple pen"

>>936553159

a + p = 7 (given)
p + a = 7. (rewritten)

p + g = 9
-(p + a = 7)
= g - a = 2

2g + a = 19
+(g - a = 2)
=3g =21
g = 7.

If g = 7, then:

p + g = 9,
p + 7 = 9
p = 2

if p = 2
a + p = 7
a + 2 = 7
a = 5

2g + a = 19?
2 x 7 + 5 = 19?
14 + 5 = 19?
19 = 19? yes.

a + g + p = x
5+ 7 + 2 = 15
x= 15

>>936553424
can you tutor my grandchildren

>>936554101
5+7=12
12+2=14

Lrn 2 math dude....

I cant, a nigger just stole my fruit

>>936554234
the last line is 27 which means the maximum value.

>>936551707 (OP)
Is that grape x grape, 2grape, or a new variable?