A cup of broth can have 870 milligrams of salt, 30% of the recommended daily allowance. What is the recommended daily amount?

1 Answer
Apr 3, 2017

See the entire solution process below:


We can rewrite this problem as:

30% of what is 870 milligrams?

"Percent" or "%" means "out of 100" or "per 100", Therefore 30% can be written as #30/100#.

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

Finally, lets call the recommended daily amount we are looking for "r".

Putting this altogether we can write this equation and solve for #r# while keeping the equation balanced:

#30/100 xx r = 870#

#color(red)(100)/color(blue)(30) xx 30/100 xx r = color(red)(100)/color(blue)(30) xx 870#

#cancel(color(red)(100))/cancel(color(blue)(30)) xx color(blue)(cancel(color(black)(30)))/color(red)(cancel(color(black)(100))) xx r = 87000/color(blue)(30)#

#r = 2900#

The recommended daily amount of salt is 2,900 milligrams.