You didn't give any choices, but the equation looks like this: 17 = 2x + 5. Solving that for x tells you that he went on a big water slide 6 times. 2 times 6 plus 5 is the $17 he spent at the park. See how well that works out?
If it takes 8 days with 10 women to make 3 tree houses, then the rate of woman per tree house is 3/80. Multiplying this by 6 and dividing by 36, you get a rate of 1/160 or 160 days. Hope this helps!