Same sign add different sign subtract that means if their both positive you add and if one is positive and the other is negative you subtract
28 mpg is the average so that is what they should expect.
For the function 5x, the range is the value of f(x) which is five times the x and the domain is the value of x which can be the ratio of f(x) and 5. For the second function which is g(x) = 5, the range is 5 all through out the graph while the domain is infinity.
