Question 211743
Let f = father's age; let s = son's age
:
"the present age of a father is three years more than three times the age of his son."
f = 3s + 3
:
"three year hence, fathers age will be 10 years more than twice the age of his son."
f + 3 = 2(s+3) + 10
f + 3 = 2s + 6 + 10
f + 3 = 2s + 16
f = 2s + 16 - 3
f = 2s + 13
:
determine their present ages.
Substitute (3s+3) for f in the above equation, find s
3s+3 = 2s + 13
3s - 2s = 13 - 3
s = 10 yrs, son's present age
then
f = 3(10) + 3
f = 33 yrs, father's present age
;
:
Check solution in the statement:
"three year hence,fathers age will be 10 years more than twice the age of his son. 
33 + 3 = 2(10+3) + 10
36 = 2(13) + 10