Suppose two children push horizontally, but in exactly opposite directions, on a third child in a wagon. The first child exerts a force of -75.0 N,...

Suppose two children push horizontally, but in exactly opposite directions, on a third child in a wagon. The first child exerts a force of -75.0 N, the second a force of +90.0 N, friction is -12.0 N, and the mass of the third child plus wagon is 23.0 kg. What is the acceleration?