Solve using substitution.
-7x + 9y = 20
y = 10

x=10

Step-by-step explanation:

1. substitute y for 10 getting -7x +9(10)=20

2. 9(10)= 90

3. with -7x+90=20 subtract 90 on both sides getting -7x= -70

4. then divide by -7 on both sides getting x=10

5. to check u substitute x with 10 and y with 10 getting -7(10)+9(10)=20. then multiply and add/subtract to get 20=20