At the science museum, there is an exhibition with 150 displays about energy.
30% of the displays are about electricity.
2/5 are about using renewable energy.

1/10 are about the use of gas
the remainder are about nuclear power. what fraction of the displays are about nuclear power?

1/5
       
This is a matter of elimination. So let's figure out how many of each display there is. 30% of 150 = 0.30 * 150 = 45 displays about electricity. 2/5 * 150 = 0.40 * 150 = 60 displays about renewable energy 1/10 * 150 = 150/10 = 15 displays about gas. The rest of the displays are about nuclear power. So 150 - 45 - 60 - 15 = 30 displays about nuclear power. Since we want a fraction, we get 30/150 But 30/150 isn't in it's simplest form. The largest number that will evenly divide both 30 and 150 is 30. So divide both the numerator and denominator by 30 (30/30)/(150/30) = 1/5 So 1/5 of the displays are about nuclear power.