Question

The value of y varies directly with x. If x = 7, then y = -40. What is the value of x when y = 51?

Answer 1

Introduce a constant,

let it be (k)

Y=KX

-40 = K(7)

K= -5.7

Then,

Y =KX

51= -5.7(X)

X = -8.95~-9