My estimate is 36$ (you may get a different estimate) and the actual answer is 36.19$ / my estimate is less than the actual solution. (Again your estimate may be different)
Explanation: round all the sporting equipment prices then add them together, minus that from 90$, and that will get you your estimate. Then add all the original sports equipment prices together to get the real total, then subtract from 90$. Then compare and contrast the two totals.