There are 18 classes in the whole school. If each class saves (5/7) kilograms of paper every day, how many kilograms of paper can the whole school save in a week?
全校有18个班，如果每个班每天节约用纸(5/7)千克，照这样计算，全校一周可节约用纸多少千克？
<gadget id="calculator">5 / 7</gadget>
<output>5/7 = around 0.714286</output>

<gadget id="calculator">(5/7) * 7 * 18</gadget>
<output>90</output>

<result>90</result>