The formula for the interest will be I = A -P
The subject of formula is a way of representing a variable in terms of other variables.
Given the expression that shows the total amount as;
A = P + I
where
p is the principal
I is the interest
Make I the subject of the formula to have:
A - P = P - P + I
I = A - P
Hence the formula for the interest will be I = A -P
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