Answer: the father is 44 years old now
Step-by-step explanation:
Let Bob's present age be represented by x
Let his father's present age be represented by y
Bob's age is 15 years less than half his father's age. This means that
x = y/2 - 15
x + 15 = y/2
y = 2x + 30
y - 2x = 30 - - - - - - - - - -1
In six years his father's age will be eleven years more than triple Bob's age. This means that
y + 6 = 3(x + 6) + 11
y + 6 = 3x + 18 + 11
y - 3x = 18 + 11 - 6
y - 3x = 18 + 11 - 6
y - 3x = 23 - - - - - - - - -2
Subtracting equation 2 from equation 1, it becomes
x = 7
y = 2x + 30
y = 2×7 + 30
y = 14 + 30
y = 44
