Coding and Decoding Questions

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

10 + 20 x 10 ÷ 20 - 8 = ?

Some equations are solved on the basis of certain system. Find the correct answer for the unsolved equation on that basis.

5 x 4 x 3 = 70 ,
6 x 5 x 4 = 140
7 x 6 x 5 = ?

If, 6x4= 12, 4x12= 24, 12x6= 36 then 6x9= ?

If ' + ' means minus , ' - ' means multiplication , ' ÷ ' means plus , and ' x ' means division , then 15 - 3 + 10 x 5 ÷ 5

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

If ALPHA = 36, BETA = 26 then DELTA = ?

If the code for MOTHER is JRQKBU then what is the code for PRINCIPAL?

If "x" stands for addition, "<" stands for subtraction, "+" stands for division, ">" stands for multiplication, "–" stands for equals to, "÷" stands for greater than and "=" stands for less than, which of the following holds true?