Question

A bag containing 5 red balls, 8 blue balls and 7 yellow balls, what % of the balls are blue?

Answer 1

There are 20 balls in the bag altogether.

If 12 of them are not blue, that means that 8 of them are blue. We can find out what percent of the blue balls are in the bag by turning it into a fraction.

The fraction $\frac{8}{20}$ represents the 8 blue balls out of the 20 balls altogether.

Now that we have our fraction, we can change it into a percent. The fraction $\frac{8}{20}$ can be reduced to $\frac{2}{5}$ by dividing both the numerator and denominator by the greatest common factor.

2 ÷ 5 = 0.4

0.4 x 100 = 40%

40% of the balls in the bag are blue.

Answer 2

5+7+8=20   which is the total number of balls that the bag contains
because out of the 20 balls only the 8 are blue, it is right to say that

8/20 = x/100 ⇒ x= (8·100)/20 ⇒ x= 800/20 ⇒ x=40

the blue balls are the 40%