For this case we have that by definition, a linear function is of the form

We have the following options:
A) 
Rewriting:

It's a quadratic function!
B) 
Rewriting:

It's a linear function!
C)
Rewriting:

It's a cubic function.
D) 
Rewriting:

It's a quadratic function!
E)
Rewriting:

It's a cubic function!
Answer:
The linear function is option B
The answer is 4 and 5 my dude ( 16 and 25)
Let’s call the number “n.” 0,32n=64 (32% is 32 per cent-, or per hundred), and n=64*100/32=100*2=200. Therefore, the answer’s D.