Coding and Decoding Questions

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

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

If PROJECT is coded as KILQVXG, then how will EGO be coded as?

If 5@1=60; 12@8=200; 16@2=180; then what is the value of 16@10=?

If "+" means "minus", "x" means "divided by", "÷" means "plus" and "-" means "multiplied by", then
76 x 4 + 4 – 12 ÷ 37 = ?

In a certain code language, '+' represents 'x', '-' represents '+', 'x' represents '÷' and '÷' represents '-'. What is the answer to the following question?

80 x 16 ÷ 4 + 2 - 8 = ?

If FRIEND is coded as HTKGPF then REVEAL will be coded as:

In a certain code language, “TALCS” is written as “UENCV”. How is “SPARK” written in that code language?