Question

If 9% of a number equals 10, find 90% of that number.

Answer 1

100

Explanation:

In this problem 10 represents 9% of a number. So, to find 90% you must multiply 10 by 10. You do this because 9% times 10 equals 90%; therefore, 100 must be 90%.

This can also be proven through cross multiplication. To set up a proportion put the percent over the number like,
`(9)/(10)=(90)/(x)`. Then cross multiply to get the equation,
`9x=900`. Finally, divide both sides to get x=100.