In order to welcome the Faith Tea Culture Festival, Xingfu Community arranged the potted flowers in a solid square, and there were still 4 pots left; if one row was added horizontally and vertically to form a larger solid square, 15 pots were missing. How many potted flowers are there in total?
为迎接信仰茶叶文化节，幸福小区把盆花排成一个实心方阵，还剩下4盆；如果横竖各增加一排成为一个大一点的实心方阵，又少了15盆．一共有多少盆花？
<gadget id="calculator">4 + 15 + 1</gadget>
<output>20</output>

<gadget id="calculator">20 / 2</gadget>
<output>10</output>

<gadget id="calculator">10 * 10</gadget>
<output>100</output>

<gadget id="calculator">100 - 15</gadget>
<output>85</output>

<result>85</result>