What is the value of x in the equation 8x – 2y = 48, when y = 4?

8x - 2y = 48
If y is given as 4, then "plug it into the equation".
8x - 2(4) = 48 
8x - 8 = 48 --> Add 8 to both sides of the equation to isolate the x variable
8x = 56 --> Divide both sides by 8
x = 7

8x - 2y = 48 ; find x  if y = 4.

x = 7

substitute y with number 4.

8x - 2(4) = 48
8x - 8 = 48

find x. transfer -8 to the other side and change its sign from negative to positive.

8x = 48 + 8
8x = 56

find x. divide both sides by 8.

8x/8 = 56/8
x = 7

to check substitute x with 7 and y with 4.

8x - 2y = 48
8(7) - 2(4) = 48
56 - 8 = 48
48 = 48