Answer:
2.5
Step-by-step explanation:
So you know that y is the total cost so you can put $12.50 in to substitute y. You then end up with the equation $12.50 = 3x+5. Nest you need too get x by itself so subtract 5 from the left and subtract 5 from the 12.50 which leaves you with $7.50 = 3x. Next we have too divide both &7.50 and 3x by 3 to get x by itself. This leaves you with 2.5 = x. Therefor your answer is 2.5.