Divide number A by number B, the quotient is (1/3), after subtracting 5 from number A, the quotient is (4/5), then what is the number A?
甲数除以乙数，商是(1/3)，甲数减去5后，商是(4/5)，那么甲数是多少．
<gadget id="calculator">4 / 5</gadget>
<output>4/5 = around 0.8</output>

<gadget id="calculator">1 / 3</gadget>
<output>1/3 = around 0.333333</output>

<gadget id="calculator">(4/5) - (1/3)</gadget>
<output>7/15 = around 0.466667</output>

<gadget id="calculator">5 / (7/15)</gadget>
<output>75/7 = around 10.714286</output>

<gadget id="calculator">(75/7) * (1/3)</gadget>
<output>25/7 = around 3.571429</output>

<result>25/7 = around 3.571429</result>