Question

please explain step by step

Answer 1

It is a fact that.
For two ordered pairs to be equal;their corresponding co-ordinate's must be equal.
i.e, x-coordinate(abscissa)and y-coordinate(ordinate) of both Co-ordinates should be equal.

X-coordinate's
→a-2=b-1
→a-b=-1+2
→a-b=1
→a=b+1 →(1)

Y-Coordinate's
2b+1=a+2
→2b-a=2-1
→2b-(b+1)=1 {from (1)}
→2b-b-1=1
→b=1+1
→b=2.

Substituting b=2in (1)
→a=2+1=3.

So...
a+b=3+2=5.

Hence, 5 is your answer...

Hope it Helps...
Regards,
Leukonov.