Find the base for the following items. 50 is 20% of what number? 50 is 20% of what number? 18 is 331⁄3% of what number? 4 is 1% of what number? 5% of what number is 90? 162⁄3% of what number is 72?

1) 50 is 20% of what number?

50 = 0.2*x Divide both sides by 0.2, or multiply each side by 5

x = 250

2) 18 is 33 and 1/3% of what number? 33 and 1/3% is equal to 1/3

18 = (1/3) x Multiply each side by 3

x = 54

3) 4 is 1% of what number? 1% is the same as 1/100

4 = (1/100) x Multiply each side by 100

x = 400

4) 5% of what number is 90? 5% is equal to 1/20

90 = (1/20) x

1800 = x

5) 16 2/3% of what number is 72? 16 and 2/3, or 16.666%, is equal to 1/6

72 = (1/6) x Multiply each side by 6

x = 432