Question

7. Find the value of:
a) The number when 40% of the number is 10

Answer 1

25

Explanation:

Let the unknown number be x

`40 \% * x = 10 \\ (40x)/(100) = (10)/(1)`

Cross Multiply

`40x = 100 * 10 \\ 40x = 1000`

Divide both sides of the equation by 40

`(40x)/(40) = (1000)/(40)`

Simplify

`x = 25`

Answer 2

Step 1) Set up a proportion

Proportion: percent / 100 = x / number

In context of the problem, the proportion is: 40 / 100 = 10 / number

Step 2) Cross-multiply and solve

100 x 10 = 40 x N

1000 = 40N

N = 25

Answer: The number is 25