a+2b=11
a-b=5
multiply the second equation by 2.when you multiply an equation by a number,the equation still remains the same,because you could divide that and get the original equation back again
now we have
a+2b=11
2a-2b=10
Add the two equations,
(a+2b+2a-2b)=11+10
3a=21
a=7
From equation 1,
a+2b=11
2b=11-a
2b=11-7
2b=4
b=2
a=7,b=2
-Prabhat
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