Coding and Decoding Questions

If 1∆-5=5, 4∆7=-28 and -1∆-3=-3, then find the value of 8∆-8 =?

In a certain code language, "READ" is written as "18514". How is "RATE" written in that code language?

In a certain code language, "OPTIMIST" is written as "LKRNRGHG". How is "PESSIMIST" written in that code language?

In a certain code language, "COPIOUS" is written as "2345389" and "GENEROUS" is written as "16760389". How is "PIGEON" written in that code language?

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

27 x 3 ÷ 30 + 5 - 125 = ?

If P denotes +, Q denotes -, R denotes '÷', and S denotes X, then: 18S36R12Q6P7 = ?

The following equation is incorrect. Which two signs should be interchanged to correct the equation? 12 - 6 x 5 + 20 ÷ 4 = 31

Some equations are solved on the basis of certain system. Find out the correct answer for unsolved equation on that basis: 4 x 5 x 8 = 584, 7 x 3 x 9 = 397, 9 x 7 x 3 = ?