Question 7668
2a+b=14
3a+b+4


Multiply one set with -1 to cancel out b:
-(2a+b=14)
3a+b+4  


-2a-b=-14
3a+b+4


add the two verticaly
a=-10




To find b, multiply the first set by 3 and the second by -2:
2a+b=14
3a+b+4 


3(2a+b=14)
-2(3a+b=4)


6a+3b=42
-6a-2b=-8 
b=34




a=-10
b=34