Suppose A and B are both natural numbers and satisfy ((A)/13)+((B)/7)=(54/91). So how much is A+B=?
设A和B都是自然数，并且满足((A)/13)+((B)/7)=(54/91)．那么A+B=多少．
<gadget id="calculator">13 * 2</gadget>
<output>26</output>

<gadget id="calculator">54 - 26</gadget>
<output>28</output>

<gadget id="calculator">28 / 7</gadget>
<output>4</output>

<gadget id="calculator">4 + 2</gadget>
<output>6</output>

<result>6</result>