To tell if two are proportional, simply multiply the numerator from the first by the denominator of the second. Then multiply the denominator from the first and the numerator for the second. If the two products are the same, then it is proportional.
since the slope is 7 the value of y should decrease as the value of x decreases. and since you went back 3 on the x, you should go down 21 on the y resulting in -3-21 which is -24
