Answer: 15.2% increase
This value is exact and hasn't been rounded.
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Work Shown
a = old value = 50
b = new value = 57.6
c = change in values
c = b-a
c = 57.6-50
c = 7.6
The positive c value tells us that we have a percent increase.
Next, divide that over the original value 50 to get:
c/a = 7.6/50 = 0.152 exactly
Move the decimal point twice to the right to arrive at 15.2%
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Here's another way to do it.
a = old value = 50
b = new value = 57.6
b/a = ratio of new over old
b/a = 57.6/50 = 1.152 exactly
Subtract off 1 to get 0.152 which then converts to 15.2% which is the final answer.