How do you define a variable and write an expression for each phrase: a number increased by the difference between six and a number?
Depending upon the interpretation, I'm going to suggest
(see below for other possibilities)
Given the phrase:
It is unclear if the intent is that both references are to the same "number". So maybe one should be a variable
might mean "six minus the number"
or it might mean "the absolute difference between six and the number"
With those interpretations in mind, the following are all possible intended expressions:
#n+(6-n)#(which would just be #6#);
#n+(6-m)#(two different "numbers");
#n+abs(6-n)#(this is the one I used in the "Answer")
#n+(abs(6-m)#(absolute difference but two different "numbers")