Identify the input and the output given the relation described:

mr. edward wants to find the cost of parking his car at a shopping center for a few hours.

Three times the sum of a number and seven is negative thirty-six. what is the number?

The u-drive rent-a-truck company plans to spend $13 million on 320 new vehicles. each commercial van will cost $25 comma 000, each small truck $50 comma 000, and each large truck  $80 comma 000. past experience shows that they need twice as many vans as small trucks. how many of each type of vehicle can they buy?

Can someone explain to me how to do