The number A is divided by the number B, the quotient is (1/3), after the number A is increased by 7, the quotient is (2/5), then what is the number A?
甲数除以乙数，商是(1/3)，甲数增加7后，商是(2/5)，那么甲数是多少．
<gadget id="calculator">2 / 5</gadget>
<output>2/5 = around 0.4</output>

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

<gadget id="calculator">(2/5) - (1/3)</gadget>
<output>1/15 = around 0.066667</output>

<gadget id="calculator">7 / (1/15)</gadget>
<output>105</output>

<gadget id="calculator">105 * (1/3)</gadget>
<output>35</output>

<result>35</result>