The students at emily's school recently raised money to the victims of a natural disaster in asia. emily's sixth grade class raised 40% of the total amount raised by the school. if emily's class raised $580, how much money did the school raise in all?

Think of it like fractions. If the total of Emily's class is 40% or $580, put it into fractions. You know the total of everything is 100% and her class raised 40%. So write it as a fraction, 40 over 100. Then, write another fraction with 580 on the top, equivalent to 40%. Then you must cross multiply and divide. So multiply 100 times 580 and divide the product by 40 to get the equivalent of 100%. Therefore, the answer would be $1450. Make sense? Maybe this picture will help.

The answer would be 24mm