In a charity donation activity, the fourth grade donated 140 yuan, the sixth grade donated 210 yuan, the fifth grade donated 3/7 of the total of the fourth and sixth grades, how much did the fifth grade donate?
在一次爱心捐款活动中，四年级捐款140元，六年级捐款210元，五年级捐款是四、六年级总数的(3/7)，五年级捐款多少元？
<gadget id="calculator">140 + 210</gadget>
<output>350</output>

<gadget id="calculator">3 / 7</gadget>
<output>3/7 = around 0.428571</output>

<gadget id="calculator">350 * (3/7)</gadget>
<output>150</output>

<result>150</result>