Auntie Li finished typing a manuscript in 3 hours, Auntie Zhang finished it in 5 hours, how many hours did they work together to finish this manuscript (4/5), what is the correct formula
打一份稿件李阿姨3小时打完，张阿姨5小时打完，两人合打几小时完成这份稿件的(4/5)，正确算式是多少
<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">1 / 5</gadget>
<output>1/5 = around 0.2</output>

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

<gadget id="calculator">(4/5) / (8/15)</gadget>
<output>3/2 = around 1.5</output>

<result>3/2 = around 1.5</result>