Coding and Decoding Questions

If 15@7=44; 5@4=18; 6@17=46; then what is the value of 17@4=?

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

If "#" means "subtraction", "&" means "division", "@" means "addition" and "%" means "multiplication", then 217 & 7 # 3 @ 2 % 7 = ?

If in a code language 3456 = ROPE and 15526 = APPLE then 54613 = ?

If 6 * 9 – 4 = 58 and 3 * 9 – 7 = 34, then in the expression A * 4 – 9 = 91, what is the value of 'A'?

If CHANTED is coded as ZEXKQBA, then how will MAY be coded as?

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

If 9@7=4; 6@1=10; 7@4=6; then what is the value of 8@2=?