What percent of 80 is 8?

1 Answer
May 29, 2018

#10%#

Explanation:

Turn this word problem into an equation. Here are a couple hints to remember:

  1. The word "is" means "equals", so wherever you see "is", use a #=# sign.
  2. Likewise, the word "of" means "multiplication", so use a #xx# sign when you see that word.
  3. Given variables to things you don't know. Since the percent is not known, give it the variable #x#.
  4. A percent is a number over a hundred. Since the percent is not known, put #x# over 100: #x/100#

#stackrel(x/100)overbrace"What percent"stackrel(xx)overbrace"of"stackrel(80)overbrace"80"stackrel(=)overbrace"is"stackrel(8)overbrace"8"#

#x/100 xx 80 = 8#

#x/100 xx 80/1 = 8#

#uarr#(anything divided by 1 is itself, so putting 80 over 1 does not change it's value)

#(x xx 80)/(100 xx 1) = 8#

#(80x)/100 = 8#

#80x = 800#

#x = 10%#