For the linear equation y = 2x + 4, if x increases by 1 point, how much will y increase?

In this item, we are given the equation and are asked for the value of the  change that will occur in the value of Y if the value of x is increased by 1. The answer to this is 2. We take for example x = 1 and x = 2. By substituting these values to the equation,
    
                   x = 1,
                                          Y = 2(1) + 4 = 6
                  x = 2, 
                                          Y = 2(2) + 4 = 8

Subtracting the first value of Y from the second value will give us the answer of 2. 

The answer is c. 7 (i think) i’m almost sure though