so radio antena is 15.85, this doesn't change with the number of floors (number of floors is the only variable)
each floor is 3.9 meters, so 3.9 times number of floors
function is f(n)=3.9n+15.85
( just for fun it can be simplified into f(n)=3.9(n+4.0641))
the function is f(n)=39n+15.85
second problem
domain is the set of numbers you can put into the function
range is the set of numbers you get from the numbers in the domain when put into the function (like the solution or result)
so if x=-7 then f(x)=-9
the range is obviously all the numbers on the right
range=-9,-4,-1
answers:
18: f(n)=3.9n+15.85
19: range=-9,-4,-1