Question

128 is 74% of what number?

Answer 1

You could write a proportion:
`\\(74)/(100)=(128)/(x)\\ cross~multiply~and~divide.\\ 128*100=12800\\12800/74=172.9\\` 128 is 74% of 172.9.

Answer 2

If we know that 128 is 74% of something, we can write it like this:

74%x=128.

If we take the percent away (percent means by hundred in latin, 1%=1/100), we'll have

74/100 *x=128


//let's multiply both sides by 100, that way we can get rid of the ugly "/100 because 100/100 = 1, and we can ignore 1 in multiplications

100*74/100 *x = 128 *100// let's simplify the left side: 100/100=1
74*x=128*100// let's calculate the right side now
74*x=12800// now we have to divide both sides by 74

x=12800/74

if we divde this, we have: 172 + 72/74. (why? see below)
We can simplify the fraction by division by 2: 172 36/37


00172
_______
12800:74
-74
___
540
- 518
-------
220
148
_________
72