Question

7x+2y=2

2x-y=10
what is the value of y?
a. y=-22
b. y=22
c. y=2
d. y=-6

Answer 1

7x+2y=2
2x-y=10

7x = 2-2y
x= (2-2y)/7------eq. 1

By substituting the value of x in eq. 1
2 {(2-2y)/7} - y =10
{ (4 -4y)/7 } -y =10
( 4-4y -7y)/7=10
4- 11y = 70
-11y = 70-4
-11y = 66
y= -6

The value of y is -6 and so, option d is correct.

Answer 2

The value of y is -6.

First, I figured out that the value of x is 2, so I plugged in two the the 2nd equation.

2(2) - y = 10 ⇒ 4 - y = 10
- 4 - 4
-----------------------
- y = 6
-----------
-1 -1

y = -6