Question

If y is 4.5 when x is 3, and y varies directly with x, find y when x is 9.

Answer 1

y=kx

when y=4.5 and x=3,
4.5=k(3)
1.5=k
therefore, y=1.5x

when x is 9, y is
y=1.5(9)
=13.5