let y = total vehicles in lot
2x + 3x = y
you know there are 96 minivans, so 3x = 96.
solve for x, x = 96/3 means x = 32 vehicles.
2x = cars = 64
3x = minivans = 96
y = total vehicles = 160. An alternate solution is to multiply 96 times 2/3 which = 64 also.