Solve the system by substitution.

x=9y
x-5y=20

x-5=20

9y-5y=20

4y=20

4y÷4=20÷4

y=5

x=9y

x=9×5

x=45

1. 22

2. 1

3. 7

4. 18

step-by-step explanation

e2020 got it right

b

step-by-step explanation:

a difference is the result of subtraction. while each of these expressions has subtraction in it, a difference will be the result when subtraction is the last operation applied in the order of operations for the expression. this means subtraction must be outside of the parenthesis. only b has this.