Whats the rate of change in y=1.5x

"Rate of change" is how much one variable changes when the other changes. In linear equations this is know as "slope" (since slope equals the change in Y relative to the change in X). Next remember that any linear equation can be written in the form: y = mx + b, where m = slope and b = y-intercept (place where line crosses the y-axis). Therefore to figure out rate of change (or slope) of a linear equation simply rewrite the equation in the y = mx + b form. In your case, the equation is already written that way. y = 1.5x (note that in this case b = 0) So in this formula m = 1.5. The rate of change is equal to 1.5. Another way this could be said is that when x increases by one unit, y will increase by 1.5 units. Plugging in any set of numbers will show this is true: If X = 1; Y = 1.5 If X = 2; Y = 3 (X increases by 1; Y increases by 1.5) If X = 3; Y = 4.5 (Again X increase by 1; Y increase by 1.5) ...