Question

Suppose y varies directly with x. Write a direct variation equation that relates x and y. y=7 1/2 when x=3

Answer 1

y/x = 2.5

Explanation:

y ∝ x

change ∝ to = by adding constant k or c

y = kx

Divide both sides by x

y/x = k, also k = y/x

Input the values

k = (7 1/2)/3. Change 7 1/2 to improper fraction to give 15/2

k = (15/2)/3

k =
`(15)/(2)` ÷ 3

Change the division sign to multiplication which will change 3 to its inverse(1/3)

k =
`(15)/(2)` ×
`(1)/(3)`

k =
`(15)/(6)`

Divide the numerator and denominator by 3 to get 5/2

k = 5/2

From y/x = k,input k into the eqn

y/x = 5/2

y/x = 2.5