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
<pre>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: {{{highlight_green(matrix(1,4, 84/4, "=", 21, years-old))}}}
That's it!! Nothing COMPLEX or CONFUSING!