Kilograms recycled before starting the recycling plan = 8
Kilograms recycled per week = 3
Number of weeks = 3
To find the number of kilograms recycled after 3 weeks, add the already recycled kilograms (8) to the product of the kilograms recycled per week (3) and the number of weeks (3)
8 + 3 (3 ) = 8+9 = 17 kg