Question

If y varies jointly with x and z and y=90 when x=2 and z=9, find x when y=105 and z=3

Answer 1

Explanation:

y & xz

y = kxz

k = y/xz

When y = 90, x = 2 and z = 9

k = 90/(2×9) = 10/2

k = 5

y = 5xz

When y = 105 and z = 3

105 = 5×3x

105 = 15x

x = 105/15

x = 7