Answer: Choice D. P = i/rt
This is the same as saying P = i/(rt). The parenthesis are preferred in my opinion to indicate we have rt in the denominator and not just r.
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Explanation:
In the original equation, prt is the same as p*r*t. So we multiply p, r and t to get prt.
This can be thought of as p*(rt). To isolate p, we undo the multiplication done to the variable p. We will divide both sides by rt to get
i = prt
i = p*(rt)
i/(rt) = p*(rt)/(rt) ... dividing both sides by rt
i/(rt) = p
p = i/(rt)