Help with Math word problem

Question

A roll of flexible tubing is 136 feet long. John Hiffman cut lengths 7 2/3 , 16 1/5, and 21 ½ from one the roll. How much of the tubing is left? Express your answer as a mixed number if necessary

Answer 1

the common denominator of 3 , 5, and 2 is 30.

7 and 2/3 = 7 and 20/30

16 and 1/5 = 16 and 6/30

21 and 1/2 = 21 and 15/30

the total is 44 and 41/30 = 44 and 1 and 11/30 = 45 and 11/30

136 minus 45 and 11/30 =

135 and 30/30 - 45 and 11/30 =

90 and 19/30