Answer: 16 years
Explanation:
Let's Bo's age be represented by x.
Since Bo' sister Anna is 3/4 his age minus 1 year and she is 11 years old, this can be formed into an equation as:
(3/4 × x) - 1 = 11
3/4x - 1 = 11
3/4x = 11 + 1
3/4x = 12
Multiply both side by 4/3
x = 12 × 4/3
x = 16
Bo's age is 16 years