Math problem need help

Question

A varies directly with B. If A = 72 when B = 90, find A when B = 190.

Answer 1

72=90k

k= 72/90 = 8/10 = 4/5

A=4B/5

A=4(190)/5 = 4(38) = 152

Answer 2

To vary directly is of the form,

y = kx, where k is the constant of proportionality. For this case.

A = kB--> 72=90k

k = 72/90 = 0.8

When B = 190

A = 0.8(190) = 152