Answer:
The youngest brother is James and his age is 18 Years.
Step wise explaination:
Lets suppose,
age of James = x
age of Brandon = 2x
age of Marshall = 2x - 11
The sum of ages of three brothers = 79
now,
finding the value of x,
x + 2x + 2x - 11 = 79
or, 5x - 11 = 79
or, 5x = 79 + 11
or, 5x = 90
or, x = 90
5
so, x = 18.
Then,
age of James = 18.
age of Brandon = 2×18 = 36.
age of Marshall = (2×18) - 11 = 25.
Therefore,
The youngest brother is James and his age is 18 Years.