Question 1154263

Twice my age plus three times my sister's age is 86. Three times my age plus four times my sister's age is 120. How old am I?
<pre>Let my age be M and my sister's, S
Then we get: 2M + 3S = 86 ------- eq (i)	
Also, 3M + 4S = 120 ------ eq (ii)	
M + S = 34 ----- Subtracting eq (i) from eq (ii)
S = 34 - M	
2M + 3(34 - M) = 86 ------ Substituting 34 - M for S in eq (i)
2M + 102 - 3M = 86
2M - 3M = 86 - 102
- M = - 16 
M, or my age is: {{{highlight_green(matrix(1,3, (- 16)/(- 1), "=", 16))}}}