Question

128 is 74% of what number?

Answer 1

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

Answer 2

You could write a proportion:$\\\frac{74}{100}=\frac{128}{x}\\ cross~multiply~and~divide.\\ 128\times100=12800\\12800\div74=172.9$ 128 is 74% of 172.9.