>>717197990
>>717198352
The game's answer is 60
However, in the first we can impose any number, we can even say she drove zero miles (the simplest and funniest way to explain this), meaning our algebraic goal is 180 miles.
In the return trip, this means she drove 150 miles and he drove 30, making the difference 30, since this means the road was 180 miles.
30 is a valid answer that does solve the equation, it's just not the answer the game expects from you.