The gardener uncle used 105 pots of roses to form a trapezoid in the middle of the square in the People's Park. There are 10 pots of roses on the top floor and 25 pots on the bottom. How many layers are these roses placed in total?
园丁叔叔用105盆月季花在人民公园的广场中间摆成了一个梯形，最顶层有10盆月季花，最底层有25盆，这些月季花一共摆了多少层？
<gadget id="calculator">10 + 25</gadget>
<output>35</output>

<gadget id="calculator">2 / 35</gadget>
<output>2/35 = around 0.057143</output>

<gadget id="calculator">105 * (2/35)</gadget>
<output>6</output>

<result>6</result>