The two given expressions on either side of the ‘=’ sign will have the same value if two terms on either side or on the same side are interchanged. Find from the given option the correct terms to be interchanged.
$$5 \times 2 + 8 \div 2 - 1 = 9 - 6 \div 3 + 6 \times 3$$

As per the given question,

$$5 \times 2 + 8 \div 2 - 1 = 9 - 6 \div 3 + 6 \times 3 $$

In this type of question, we will solve it by the given option, by hit and trial method.

If we check option A  (8, 9)

L H S $$5 \times 2 + 8 \div 2 - 1 $$

we replace 8 = 9

then $$ 5 \times 2 + 9 \div 2 -1 $$ = $$ 5 \times 2 + 4.5 -1 $$ =  10  - 3.5 

=  6.5 

R H S $$ 9 - 6 \div 3 + 6 \times 3 $$ 

we replace 9 = 8

then $$ 8 - 6 \div 3 + 6 \times 3 $$ =  8 - 2 + 6 x 3  = 24

L H S not equal to  RHS

Then we check option B (  5, 9)

L H S $$5 \times 2 + 8\div 2 - 1 $$

we replace 5 = 9

then $$9 \times 2 + 8 \div 2 -1$$ = 18 + 4 -1 = 21 

R H S $$9 - 6 \div 3 + 6 \times 3 $$ 

we replace 9 = 5  

then $$ 5 - 6 \div 3 + 6 \times 3 $$ = 5 - 2 +18 = 21

 then  L H S = R H S  is right

 then  B ( 5, 9 )  is verified.