Question

What is the value of `y` when `x` equals 20 in the equation `-2x+4y=-4`?

Answer 1

y = 9

Explanation:

Substitute x = 20 in for x in the equation

hence : `-2xx20 + 4y = -4 → -40 + 4y = -4`

now add 40 to both sides

thus : -40 + 4y + 40 = - 4 + 40

which gives : 4y = 36 , and dividing both sides by 4, to obtain y

`rArr (cancel(4) y)/cancel(4) = 36/4 rArr y = 9`

check : -40 + 4(9) = -40 + 36 = -4