The school organizes students to collect plastic bottles. The sixth grade collected 250. The sixth grade collected 70 less than the fifth grade. How many plastic bottles did the fifth grade collect?
学校组织同学们收集塑料瓶，六年级收集了250个，六年级收集的比五年级的2倍少70个，五年级收集塑料瓶多少个？
<gadget id="calculator">250 + 70</gadget>
<output>320</output>

<gadget id="calculator">320 / 2</gadget>
<output>160</output>

<result>160</result>