Need help with 5X+8

Question

trying to explain this to my son.

A mail-order supplier of small electrical parts charges a shipping fee of $8, plus $5 for each push-button light switch ordered. If x is the number of push-button switches ordered, then the expression for the total cost of an order is 5x + 8. Which table shows the total cost for the given number of switches ordered?

Answer 1

The table must obey the formula

 

so if you multiply the number under column x by 5 and then add 8, the number in the

same row , next column had better be that result

 

For example,  for X=5 light switches, the cost shall be 5x5+8 = 25+8 = 33