A number a is less than b (4/5) of B number, and the formula for B number is (a+b)/how much
甲数a，比乙数的(4/5)少b，表示乙数的式子是(a+b)/多少
<gadget id="calculator">4 / 5</gadget>
<output>4/5 = around 0.8</output>

<result>4/5 = around 0.8</result>