Answer:
It depends on what you meant. See below.
Step-by-step explanation:
What you wrote means this:
[tex] f(x) = \dfrac{4}{9}x + 7 [/tex]
This is linear.
If you meant this
[tex] f(x) = \dfrac{4}{9x} + 7 [/tex]
or this
[tex] f(x) = \dfrac{4}{9x + 7} [/tex]
then it's non-linear.
An x in the denominator makes a function non-linear.