B. The variables x and y vary directly. Use the values to find the constant of proportionality and write and equation that relates x and y.

1. y - 4; x = 6
2. y = 2; x = 10

1 answer

x goes from 6 to 10, y goes from -4 to 2
so x changed by 4, y changed by 6

y=mx+b
y=6/4 * x + b now test the first point
-4=6/4 * 6+b
b=-4 -9=-13

y=1.5 x -13