Coding and Decoding Questions

If 80&10 = -8, 50&2 = -25 and 80&16 = -5, then find the value of 20&5 = ?

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

80 + 2 ÷ 25 + 5 - 10 = ?

 In a certain code language, “PRANK” is written as “RUESQ”. How is “RATES” written in that code language?

If "S" denotes "multiplied by", "V" denotes "subtracted from", "M"denotes "added to" and "L" denotes "divided by", then

343 L 7 S 6 V 94 M 11 =?

In a certain code, 134 is AGE and 92706 is INERT. What is 016923?

If "*" denotes "added to", "&" denotes "divided by", "@" denotes "multiplied by" and "%" denotes "subtracted from", then 136 & 8 @ 7 % 3 * 7 = ?

If P denotes multiply, T denotes subtraction, M denotes addition, B denotes division then 28B7P8T6M4 = ?

If EXPLAIN is coded as BUMIXFK, then how will GYM be coded as?