If John had to mow 8 lawns, but he forgot to mow 2 lawns, we have to subtract 2 from 8 to see how many lawns he actually mowed.
8-2=6
John mowed 6 lawns!
For each lawn John mowed, he earned 3 dollars. So, we have to multiply the number of lawns he mowed, 6, by the amount of dollars he earned per lawn, 3. Multiplying 6*3 is the same as adding 3+3+3+3+3+3!
6*3=18
John earned $18!
Hope I helped! :)
