Given that △+□+△=15, □+□+□+□=16, find out how much △+□=.
已知△+△+△=15，□+□+□+□=16求△+□=多少．
<gadget id="calculator">15 / 3</gadget>
<output>5</output>

<gadget id="calculator">16 / 4</gadget>
<output>4</output>

<gadget id="calculator">5 + 4</gadget>
<output>9</output>

<result>9</result>