There are several seedlings of A and B in a certain nursery. The average height of seedlings of type A is 80 cm, the average height of seedlings of type B is 200 cm, and the average height of seedlings of type A and B is 150 cm. If there are 30 seedlings of type A, then , How many saplings of type B are there?
某苗圃种有甲、乙两种树苗各若干株，甲种树苗平均高80厘米，乙种树苗平均高200厘米，甲、乙两种树苗平均高150厘米，如果甲种树苗有30株，那么，乙种树苗有多少株？
<gadget id="calculator">150 * 30</gadget>
<output>4_500</output>

<gadget id="calculator">30 * 80</gadget>
<output>2_400</output>

<gadget id="calculator">4_500 - 2_400</gadget>
<output>2_100</output>

<gadget id="calculator">200 - 150</gadget>
<output>50</output>

<gadget id="calculator">2_100 / 50</gadget>
<output>42</output>

<result>42</result>