SOLUTION: Please help me to solve this problems using to variables "the sum of ages of the son and his father is 69. If the fathers age is twice as his sons age increasedby 9 find their pres

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Question 490890: Please help me to solve this problems using to variables "the sum of ages of the son and his father is 69. If the fathers age is twice as his sons age increasedby 9 find their present ages".
Answer by ankor@dixie-net.com(22740) About Me  (Show Source):
You can put this solution on YOUR website!
let f = father's present age
let s = son's present age
:
Write an equation for each statement
:
"the sum of ages of the son and his father is 69."
f + s = 69
:
If the fathers age is twice as his sons age increased by 9,"
f = 2s + 9
:
Use the above equation for substitution in the 1st equation
f + s = 69
replace f with (2s+9)
2s + 9 + s = 69
2s + s = 69 - 9
3s = 60
s = 60%2F3
s = 20 yrs is the son's age
:
You can use the 2nd equation to find the father's age, substitute 20 for s.
Then check their sum in the 1st equation.