There are several fountain pens and ballpoint pens, the total number is between 101-109. It is known that the number of fountain pens is 4 times the number of ballpoint pens. Then, how many pens are there?
有若干支钢笔与圆珠笔，总数在101-109之间，已知钢笔的支数是圆珠笔支数的4倍，那么，钢笔有多少支．
<gadget id="calculator">105 / 5</gadget>
<output>21</output>

<gadget id="calculator">21 * 4</gadget>
<output>84</output>

<result>84</result>