Question 151459
I'LL DO THE FIRST 2 TO SHOW YOU HOW IT'S DONE.
THE LAST 2 ARE FOR YOU TO PRACTICE WITH NOW THAT YOU HAVE THE PROCEDURE.
--------------------------------------------------------------------
a)X + Y=7 
X + 2Y = 11 SUBTRACT.
---------------
-Y=-4
Y=4 ANSWER.
X+4=7
X=7-4
X=3 ANSWER.
PROOF
3+2*4=11
3+8=11
----------------------------------------------------------------
b)3X + 7Y = 24 MULTIPLY BY -3 & ADD.
 9X + 5Y = 24
-9X-21Y=-72 ADD.
---------------
-16Y=-48
Y=-48/-16
Y=3 ANSWER.
9X+5*3=24
9X+15=24
9X=24-15
9X=9
X=9/9
X=1 ANSWER.
PROOF:
3*1+7*3=24
3+21=24
24=24