Mom bought a piece of soap for 3 yuan and 50 cents. After paying, the salesperson returned 50 cents. How much did the mother pay?
妈妈买了1块3元5角的香皂，付钱后，售货员找回5角钱．妈妈付了多少元钱．
<gadget id="calculator">5 / 10</gadget>
<output>1/2 = around 0.5</output>

<gadget id="calculator">(1/2) + 3</gadget>
<output>7/2 = around 3.5</output>

<gadget id="calculator">(7/2) + (1/2)</gadget>
<output>4</output>

<result>4</result>