This problem boils down to 5/6 - 1/4
To subtract these fractions you need a common denominator.
I'll use 12
The first fraction becomes 10/12 and the second fraction becomes 3/12
10/12-3/12 = 7/12
So Jacob is 7/12 of a foot taller than Linda.
Also note than since 12 inches = 1 foot, you could say Jacob is 7 inches taller than Linda