Question

solve this above question ​

Answer 1

We can't guess the answer... It is too much work for our brains...

So we usually variable a, b, c and d to solve the question.

Look in the picture

We are given the equations,

$a+d=8$ -No.1

$a+b=13$ -No.2

$b-c=6$ -No.3

$c+d=8$ -No.4

We use elimination method

because it ELIMINATES one by one.

Add No.1 to No.2

$2a+b+d=21$

Add No.3 to No.4

$b+d=14$

Now, subtract above → below

$2a=7$ ∴$a=7/2$

Put a into No.2

$7/2+b=13$ ∴$b=19/2$

Put b into No.3

$19/2-c=6$ ∴$c=7/2$

Put c into No.4

$7/2+d=8$ ∴$d=9/2$