Answer:
5
Step-by-step explanation:
We know that g is an invertible function and so it must also be a one-to-one function.
This means that each input is paired with exactly one output and that each output is paired with exactly one input.
We know that g(a)=7g and g(5)=7. If the output of 7 is to be paired with exactly one input, then a must be equal to 5.
