Coding and Decoding Questions

If 4 x 5 x 2 = 524, 3 x 7 x 2 = 723 and 6 x 8 x 7 = 876 then 9 x 4 x 5 = ?

If BLACKSMITH is coded as CNBELUNKUJ, then CHILDREN will be coded as ?

If "+" means "minus", "x" means "divided by", "÷" means "plus" and "-" means "multiplied by", then
300 x 10 – 5 + 36 ÷ 57 = ?

In a certain code language, “MAYOR” is written as “NBZPS”. How is “PLAYER” written in that code language?

In a certain code language, "CERTAIN" is written as "DFSTBJO". How is "CRICKET" written in that code language?

If CROWNED is coded as APMULCB, then how will TAP be coded as?

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=?