Y = 
You can get this by switching the x and f(x) in the equation and then solve for f(x)
f(x) = 19/2x - 21 ---> now switch them
x = 19/2f(x) - 21 ---> now add 21 to both sides
x + 21 = 19/2f(x) ---> now multiply by 2/19 on both sides
(2x + 42)/19 = f(x) ---> ANSWER
You can get this by switching the x and f(x) in the equation and then solve for f(x)
f(x) = 19/2x - 21 ---> now switch them
x = 19/2f(x) - 21 ---> now add 21 to both sides
x + 21 = 19/2f(x) ---> now multiply by 2/19 on both sides
(2x + 42)/19 = f(x) ---> ANSWER