Suppose two children push horizontally, but in exactly opposite directions, on a third child

in a sled. The first child exerts a force of 76 N, the second a force of 93 N, kinetic friction is 7.5 N, and

the mass of the third child plus sled is 21.5 kg.

Using a coordinate system where the second child is pushing in the positive direction, calculate the

acceleration in m/s².