Need help please. i appreciate it

Nneeedd 1.find the residual if you know the actual number is 5.2 and the predicted value is 4.8

Tim's phone service charges $23.06 plus an additional $0.22 for each text message sent per month. if tim's phone bill was $28.56, which equation could be used to find how many text messages, x, tim sent last month?

Daniel bought a computer game for $25 and later sold it to thomas for a 40% profit. how much did daniel sell the computer game for?