On the Arbor Day on March 12, 531 trees were planted by boys and girls. It is known that there are 51 boys and 45 girls. Each of the boys will plant 6 trees, and the rest will be left to the girls. How many trees will each of the girls plant?
3月12日植树节，男女生共植树531棵．已知男生有51人，女生有45人，男生每人植树6棵，余下的留给女生，问女生每人植树多少棵？
<gadget id="calculator">51 * 6</gadget>
<output>306</output>

<gadget id="calculator">531 - 306</gadget>
<output>225</output>

<gadget id="calculator">225 / 45</gadget>
<output>5</output>

<result>5</result>