You simply have to add the two numbers together, however, you have to convert everything into inches only. You know that there are 12 inches in one foot. To calculate the length of the longer slide, it is simply doing 12 feet TIMES 12 (since there are 12 inches in one foot). This makes 144 inches. Add 1/2 feet in there, this is adding 1/2 of 12 inches, which is 12/2=6 inches. The long slide is therefore 144+6= 150 inches. Now you want to convert 3 feet and 7 inches into inches only. 3 feet TIMES 12 = 3x12=36 inches. Add 7 inches to this, and you will get 36+7=43 inches. To know how long the small slide is, subtract 43 inches from 150 inches, and this will give you 150-43=107 inches. So, the small slide is 107 inches. :)
