If both a and b are non-zero natural numbers and satisfy ((a)/4)+((b)/7)=(27/28), then a+b=how much.
如果a和b都是非零自然数，并且满足((a)/4)+((b)/7)=(27/28)，那么a+b=多少．
<gadget id="calculator">1 + 5</gadget>
<output>6</output>

<result>6</result>