Question

A+B=16,A-B=8 then A=
how much

Answer 1

a+b=16
a-b=8
from first eq a=16-b putting a in eq 2 we get 
a-b=8
16-b-b=8
-2b=-8    (-ve sign get cancled)
2b=8
b=4      now putting b=4 in 1 eq we will get
a+b=16
a+4=16        a=12,b=4

Answer 2

Value of A = 12 from given equation A + B = 16 & A – B = 8  

Solution:

Given:      A + B = 16_______ (1)

                  A – B = 8_______ (2)

The above two equations represent a situation which tells that A>B because the difference of A and B is positive which is only possible if A>B.

In order to solve such kind of equations we add the both of the equations and then by adding the two equations we eliminate B and we get A    

Adding (1) and (2) we get

 2A = 24

A = 12