SOLUTION: Mr.lin is four times as old as his daughter. The sum of their ages is twelve years less than twice the difference of their ages. How old is mr.lin? The answer choices are 12,24,36

Algebra ->  Human-and-algebraic-language -> SOLUTION: Mr.lin is four times as old as his daughter. The sum of their ages is twelve years less than twice the difference of their ages. How old is mr.lin? The answer choices are 12,24,36       Log On


   

Question 606887: Mr.lin is four times as old as his daughter. The sum of their ages is twelve years less than twice the difference of their ages. How old is mr.lin? The answer choices are 12,24,36 & 48
Answer by ankor@dixie-net.com(22740) About Me  (Show Source):
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Mr.lin is four times as old as his daughter.
The sum of their ages is twelve years less than twice the difference of their ages.
How old is mr.lin?
:
Let L = Mr Lin's age
Let d = daughter's age
:
Write an equation for each statement:
:
"Mr.lin is four times as old as his daughter."
L = 4d
:
"The sum of their ages is twelve years less than twice the difference of their ages."
L + d + 12 = 2(L-d)
L + d + 12 = 2L - 2D
d + 2d + 12 = 2L - L
3d + 12 = L
Replace L with 4d (from the 1st statement)
3d + 12 = 4d
12 = 4d - 3d
d = 12 yrs is daughters age
then
4(12) = 48 is Mr Lin's age
:
:
See if that checks out in the statement:
"The sum of their ages is twelve years less than twice the difference of their ages."
48 + 12 + 12 = 2(48 - 12)
72 = 2(36)