SOLUTION: The sum of Sam and Mary's age is 60. Twelve years ago, Sam was three times as old as Mary. 1. Write a system of equations to represent this situation. 2. Find Mary's age now

Question 1145713: The sum of Sam and Mary's age is 60. Twelve years ago, Sam was three times as old as Mary.
1. Write a system of equations to represent this situation.
2. Find Mary's age now
Found 2 solutions by ankor@dixie-net.com, MathTherapy:
Answer by ankor@dixie-net.com(22740) (Show Source): You can put this solution on YOUR website!
The sum of Sam and Mary's age is 60.
s + m = 60
m = (60-s)
Twelve years ago, Sam was three times as old as Mary.
s - 12 = 3(m-12)
s - 12 = 3m - 36
s = 3m - 36 + 12
s = 3m - 24
:
1. Write a system of equations to represent this situation.
in the above equation, replace m with 60-s
s = 3(60-s) - 24
s = 180 - 3s - 24
s + 3s = 180 - 24
4s = 156
s = 156/4
s = 39 yrs is sam's age
:
2. Find Mary's age now
60 - 39 = 21 yrs is Mary's age
:
:
:
See if that checks out
39 - 12 = 3(21-12)
27 = 3(9)
Answer by MathTherapy(10552) (Show Source): You can put this solution on YOUR website!

The sum of Sam and Mary's age is 60. Twelve years ago, Sam was three times as old as Mary.
1. Write a system of equations to represent this situation.
2. Find Mary's age now

Let Sam's and Mary's ages be S and M, respectively
Then equation 1 is: S + M = 60
Equation 2: S - 12 = 3(M - 12)____S - 12 = 3M - 36_____S - 3M = - 24
S + M = 60 ----- eq (i)
S - 3M = - 24 ---- eq (ii)
4M = 84 ----- Subtracting eq (ii) from eq (i)
M, or Mary is:
That's it!! Nothing COMPLEX or CONFUSING!
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