Answer:
A
Step-by-step explanation:
Because I am smart and u best mark me brainlist
Without calculating we can say that the system with the original cost $60 ( the cheaper system ) had a greater percent decrease.
This is because $10 is a greater percentage of $60 than it is of $90 ( if we calculate it is 16.66% in the first case and 11.11% in the second case).
Step by step subtract 20 from both sides and then subtract 20 from 9 to get -11
Answer: C=-11
The answer would be C
2x + 9 = 21
1. 2x = 12
2. x = 6
