Question

The order pairs (12,32), (x,40), (18,48), (21,y) represent a proportional relationship. Find the values of x and y. Select the two correct answers.

Answer 1

We can notice that the first entry of each of the pairs of numbers is increasing by 3

12, x, 18, 21

So, we expect x=15

And, similarly, in the case of the second entry

32,40,48,y

Notice that they increase by 8 (32+8=40, 40+48=48), then y=48+8=56

We already have x and y, we only need to find the proportional relationship

For this, we can plot the points on a plane, as the follow drawing:

It's a line!

Writing down its equation:

In general, given two points in a line, the equation of a line is given by: