There are 30 footballs in the school sports room, volleyballs (2/3) and basketballs (2/7). How many basketballs are there in the school? (solution by equation)
学校体育室有足球30个，排球个数是足球的(2/3)，又是蓝球的(2/7)，学校有多少个篮球？(用方程解)
<gadget id="calculator">2 / 3</gadget>
<output>2/3 = around 0.666667</output>

<gadget id="calculator">30 * (2/3)</gadget>
<output>20</output>

<gadget id="calculator">7 / 2</gadget>
<output>7/2 = around 3.5</output>

<gadget id="calculator">20 * (7/2)</gadget>
<output>70</output>

<result>70</result>