Xiao Zhang and Xiao Wang set off from Village A and Village B at the same time respectively, and walked back and forth between the two villages (they returned immediately after reaching the other village). They met for the first time at a distance of 3.5 kilometers from Village A. They met for the second time at 2 kilometers away, and asked how many kilometers away from Village B was the place where the two met for the fourth time. (encounter refers to meeting face to face)
小张与小王分别从甲、乙两村同时出发，在两村之间往返行走(到达另一村后就马上返回)，他们在离甲村3.5千米处第一次相遇，在离乙村2千米处第二次相遇，问他们两人第四次相遇的地点离乙村多少千米．(相遇指迎面相遇)
<gadget id="calculator">3.5 * 3</gadget>
<output>10.5</output>

<gadget id="calculator">10.5 - 2</gadget>
<output>8.5</output>

<gadget id="calculator">3.5 * 7</gadget>
<output>24.5</output>

<gadget id="calculator">8.5 * 2</gadget>
<output>17</output>

<gadget id="calculator">24.5 - 17</gadget>
<output>7.5</output>

<gadget id="calculator">8.5 - 7.5</gadget>
<output>1</output>

<result>1</result>