You can't make 5a + d -bc shorter, I will explain why. Let say a is an apple, d is ice cream and bc is an pineapple. You have 5 apples, 1 ice cream and you have lost you pineapple so it minus 1. You can't add everything because they are different thinks. You can only say I have 5 apple, 1 ice cream and minus one pineapple. So you can't make 5a + d -bc shorter because they are different
