18.The area A of a rectangle varies jointly as the length and the width. If A = 72sq.m when
the length is 9m and the width is 8m, find the area of a rectangle whose length is 6m and whose width
is 4m.
a. 10 sq.m
b. 24 sq.m
c. 20 sq.m
d. 48 sq.m
19. If x varies directly as y and inversely as z, and x = 4 when y = 3 and z = 9, find the value of
un 10-
x when y = 2, and z = 8.
a. x= 3
b. x = 4
c. x = 6
d.x= 8
20. If x varies directly with y and inversely with z, and x = 24 when y = 16 and z = 2, find y
when x = 6 and z = 5.
a. y = 5
b. y = 6
c. y = 8
d. y = 10​