Question

The variables y and x have a proportional relationship, and y = 7 when x = 2.

What is the value of x when y = 21?

Answer 1

Explanation:

The Ratio of y : x equals to 7 : 2. Multyplying both number by three, y equals 21 and x equals 6

Answer 2

x=6

Explanation:

We can use ratios to solve this. The ratio has to stay constant if they are proportional. Put y in the numerator and x in the denominator.

7 21

----- = ----

2 x

We can solve using cross products.

7*x =2 *21

7x = 42

Divide each side by 7

7x/7 = 42/7

x =6