It is linear because both variables have an exponent of 1. (FYI: one of the exponents can be 0 and still be a linear equation).
2x + y = 8
-2x -2x
y = -2x + 8 ⇒ slope (m) = -2 and y-intercept (b) = 8
plot the y-intercept (0, 8). then plot the next point by counting the rise over run from the y-intercept. count 2 units down and 1 unit to the right = (1, 6).
