So Zane starts at -25 meters, then, after 35 seconds, he makes it to the top. The questions is asking how high he climbed every 7 seconds. As we know, 7x5 is equal to 35. this means that we can divide 35 and 25 by 5 to get the answer. 25/5 is equal to 5, so that means he climbed 5 meters every 7 seconds. I hope this helps!