Question

Y varies directly as x if y = 3 when x = 12 find y when x = 20

Answer 1

y = kx, k being a constant

--------------------------------------
Find k :
--------------------------------------
When x = 12, y = 3
3 = k(12)
k = 3/12
k = 1/4

Equation : y = 1/4 x

--------------------------------------
Find y when x = 20:
--------------------------------------
When x = 20,
y = 1/4 (20)
y = 5

--------------------------------------
Answer: y = 5
--------------------------------------