A project can be completed by A alone in 5 hours and B by himself in 3 hours. How many hours does it take for A and B to work together? What is the correct column
一项工程，甲单独做5小时完成，乙单独做3小时完成．甲、乙合做共需要多少小时？正确列式为多少
<gadget id="calculator">1 / 5</gadget>
<output>1/5 = around 0.2</output>

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

<gadget id="calculator">(1/5) + (1/3)</gadget>
<output>8/15 = around 0.533333</output>

<gadget id="calculator">1 / (8/15)</gadget>
<output>15/8 = around 1.875</output>

<result>15/8 = around 1.875</result>