The students played a coin toss game. The rules of the game are: toss a coin, and when the coin falls, it will go forward 10 steps when its head is up, and it will go back 5 steps if its back is up. Xiao Ming tossed the coin 15 times, and walked 60 meters forward. How many times did Xiao Ming flip the coin and it came up heads?
同学们玩抛硬币游戏．游戏的规则是：将一枚硬币抛起，落下后正面朝上就向前走10步，背面朝上就后退5步．小明一共抛了15次硬币，结果向前走了60米．小明抛的硬币，正面朝上多少次？
<gadget id="calculator">15 * 10</gadget>
<output>150</output>

<gadget id="calculator">150 - 60</gadget>
<output>90</output>

<gadget id="calculator">10 + 5</gadget>
<output>15</output>

<gadget id="calculator">90 / 15</gadget>
<output>6</output>

<gadget id="calculator">15 - 6</gadget>
<output>9</output>

<result>9</result>