You are making pies to sell at a fundraiser. it costs $3 to make each pie, plus a one-time cost of $20 for a pastry blender and rolling pin. you plan to sell the pies for $5 each.

3*pie(or p)+20

It is $5 per pie.

We know the answer has to end is 0 or 5 since all multiples of 5 end it those. The first time 3 goes into 0 or 5 is 15. (3*5=15). You substitute to get 3*5+20=35. You sell 7 pies because 7*5=35, which is the cost for the making of the pies and the rolling pins.