Sagot :
Step-by-step explanation:
1.) y is directly propotional to x and y=7 when x=21, tind the constant of variation.
y = kx
7 = k21
k = 1/3
2.) z varies directly as w and z=50 when w=40, find the equation of variation.
z = kw
50 = k40
k = 50/40
k = 5/4