A low-calorie bread has 150 calories in a 3-slice serving. This is 20% fewer than the number of calories in a serving of regular bread. How many calories are in the same size serving of regular bread?

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Answer 1 · 2018-05-26T08:08:26

#187.5# calories

This is an example of reverse percentage, because you know the value of a changed amount, but not the original #(100%)#.

Use direct proportion to compare the two values and the two percentages.

#20%# less than #100%# means that the #150# calories represents #80%#. We want to find #100%#

#x/100 = 150/80" "(larr"calories")/(larr"percent")#

#x = (150xx100)/80#

#x= 187.5# calories

Note that this is the same calculation as increasing a number in the ratio #100 : 80#

​ A low-calorie bread has 150 calories in a 3​-slice serving. This is 20​% fewer than the number of calories in a serving of regular bread. How many calories are in the same size serving of regular​ bread?