Word problem involving Bob and James finishing the roof of a house

Question

Bob and James are finishing the roof of a house. Working together they can shingle the house in 5 hours and 30 minutes. Working alone, Bob can shingle the roof in 17 hours. How many hours would it take James to shingle the same roof by himself? Round your answer to the nearest tenth if necessary.

Answer 1

1/5&1/2 = 1/17 + 1/J, solve for J

2/11 = 1/17 + 1/J

1/J = 2/11 - 1/17

J= 11(17)/23 = about 81.3

8.1 not 81.3

Endless computer glitches, not allowing me to correct anything, just "error" messages,