Please help me with what the slope of the linear function is

Find the number of positive three-digit even integers whose digits are among 9, 8, 7,5, 3, and 1.

When i add money am i supposed to make it like this 7+12 or 7.00+12.00 because i got 19 dollars for my answer

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?