Question

If a varies directly as b, and a = 28 when b = 7, find b when a = 5.

Answer 1

a = kb

28 = k*7
k = 28/7=4

a = 4*b
plug in and see what you get

Answer 2

a= 28, b=7
a= 5 , b=?
just multiply crossly.
28b=35
So b=1.25.