A landscaper charges you $102 for 8 bushes
Divide 102 with 8
102/8 = 12.75
Each plant costs $12.75
If you are putting 12, multiply $12.75 with 12
12.75 x 12 = 153
If you are putting 12, the cost would be $153
If you are putting 20 (12 more), multiply $12.75 with 20
12.75 x 20 = 255
If you are putting 12 more (20 in all), the cost will be $255
hope this helps