text: what is the sum of 6 ft. 10 in. and 8 ft. 9 in.? a. 14 ft. 7 in. b. 15 ft. 7 in. c. 13 ft.19 in. d.15ft.19in.?   to answer this question, simply add the feet (6 + 8 = 14) then add the inches (10 + 9 = 19), you then get 14 ft 19 inches.  since 19 inches is longer than a foot (which is twelve inches), take the 19 inches and divide it by 12.  19 divided by 12 = 1, remainder 7.  this means that when you have 19 inches, it is 1 ft, 7 inches.  so, add the 1 ft 7 inches to the 14 feet you originally found when you added 6 ft plus 8 ft.  the answer is then 15 feet 7 inches.