Question

y varies inversely with x. If y = 40 when x = 16, find x when y =-5.

Answer 1

y varies directly with x m eans
y=kx where k is constant

y=40
x=16
find k
40=k16
divide both sides by 16
5/2=k

y=5/2x

y=-5 find x
-5=5/2x
times 2/5 both sides to cancle fraciton (5/2 times 2/5=10/10=1)
-10/5=x
-2=x

x=-2