1. Observe problem
1-(1/8+1/12+1/2)
Make all common denominator
The Least common multiple of 8,12, and 2 is 24
1-((3+2+12)/24)=
1-17/24=
7/24
Therefore, 28 years make up 7/24 of his life.
Simplifying, he grows 4 years for every 1/24 of his life
4 times 24 is 96, so
Fred is 96 currently(that's pretty old)