The ratio of A and B's original money is 3:4, and later A gives B 50 yuan. At this time, A's money is B's (1/2), how much A originally had.
甲、乙两人原来钱数的比是3：4，后来甲又给乙50元钱，这时甲的钱数是乙的(1/2)，甲原来有多少元．
<gadget id="calculator">3 + 4</gadget>
<output>7</output>

<gadget id="calculator">3 / 7</gadget>
<output>3/7 = around 0.428571</output>

<gadget id="calculator">1 + 2</gadget>
<output>3</output>

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

<gadget id="calculator">(3/7) - (1/3)</gadget>
<output>2/21 = around 0.095238</output>

<gadget id="calculator">50 / (2/21)</gadget>
<output>525</output>

<gadget id="calculator">525 * (3/7)</gadget>
<output>225</output>

<result>225</result>