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[Community Question] Algebra-Precalculus: working with traded numbers

One of our user asked:

A man want 762 by a number, but he trade it and its quotient result 13 and its rest was 13. What the quotient and rest of the original number? $$ q = ?; r=? $$ $$ 762 = q \cdot \overline{ ab } + r $$ $$ 762 = 13 \cdot \overline {ba} + 21 $$

Another way to write this is: $$ \frac{762-r}{ \overline{ba}}=r $$ $$ \frac{762-21}{ \overline{ba}}=13 $$


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