Question

Three-sevenths of a number is 21. Find the number.

the number is 9
the number is 27
the number is 49

Answer 1

Explanation:

The number is 49, First do 21 / 3 to find what 1/7 of the number is. We get 7, so we know 1/7 is 7 so if we do 7 x 7 we will have 7/7 or one whole and 7x7 is 49. Hope this helps

Answer 2

The number is 49

Explanation:

Let the number be x

From the question,
`(3)/(7)` of x = 21

`(3)/(7)` × x = 21

`(3x)/(7)` = 21

Multiply both-side of the equation by 7

`(3x)/(7)` × 7 = 21 × 7

(On the left-hand side of the equation, 7 at the numerator will cancel-out 7 at the denominator leaving us with just 3x)

3x = 147

Divide both-side of the equation by 3

`(3x)/(3)` =
`(147)/(3)`

(On the left-hand side of the equation 3 at the numerator will cancel-out 3 at the denominator, while on the right-hand side of the equation 147 will be divided by 3)

x =
`(147)/(3)`

x=49

Therefore the number is 49