Take Saturdays total of $620 and subtract Fridays total of $460 to get $160. Divide that by the difference of the number of pies sold on Friday and Saturday to get $8. Take the $8 and multiply by number of pies sold on Friday (20) to get $160. Take that number and subtract it from the total sold on Friday ($460) to get $300. Divide that by how many cakes were sold on Friday (30) and get $10. So therefore:
