You have the following equation:
7x - 2y = 8
In order to find an equivalent expression, you proceed as follow:
7x - 2y = 8 subtract 7x both sides
-2y = 8 - 7x divide both sides by -2
y = 8/(-2) - 7x/(-2)
y = -4 + (7/2)x
y = (7/2)x - 4
Hence, the equivalent equation is the line y = (7/2)x - 4
