90 is 20% more than what?

1 Answer
Jan 7, 2017

Answer:

See full explanation below:

Explanation:

We can write this as:

#90 = x + (20%# of #x)#

"Percent" or "%" means "out of 100" or "per 100", Therefore 20% can be written as #20/100#.

When dealing with percents the word "of" means "times" or "to multiply".

So we can rewrite the equation as and solve for #x#:

#90 = x + (20/100 xx x)#

#90 = x + 20/100x#

#90 = 100/100x + 20/100x#

#90 = 120/100x#

#color(red)(100)/color(blue)(120) xx 90 = color(red)(100)/color(blue)(120) xx 120/100x#

#9000/color(blue)(120) = cancel(color(red)(100))/cancel(color(blue)(120)) xx color(blue)(cancel(color(black)(120)))/color(red)(cancel(color(black)(100)))x#

#75 = x#

#x = 75#

90 is 20% more than 75