Coding and Decoding Questions

If 4 * 2 = 3 and 8 * 4 = 3 , then 21 * 7 = ?

In the following question, by using which mathematical operators will the expression become correct?
27 ? 9 ? 18 ? 24 ? 12

If '÷' stands for subtraction,'-' stands for addition,'x' stands for division and '+' stands for multiplication, then which one of the following equation is correct?

In a certain code language, “MAKER” is written as “PDNHU”. How is “TOOLS” written in that code language?

If "P" denotes "multiplied by", "R" denotes "subtracted from", "S" denotes "added to" and "Q" denotes "divided by", then 6 P 7 S 169 Q 13 R 5 = ?

In a certain code language, "RUMOUR" is written as "MURRUO". How is "RACKET" written in that code language?

In a certain code language, '-' represents '+', '+' represents 'x', 'x' represents '÷' and '÷' represents '-'. Find out the answer to the following question.

6 x 6 ÷ 10 - 8 + 2 = ?

If MIGRANT is coded as LHFQZMS, then how will GEL be coded as?