Line d and c are bother parallel but the three options would be them
You need to find "two-fifths of 30." Of here means multiplication:
There are 12 athletes in the club.
For each increment in x, the output is multiplied by 2. The function could be written the way a geometric sequence can be written:
... f(x) = 5·2^(x-1)
Or, it could be simplified to ...
... f(x) = (5/2)·2^x
The first 5 terms will be
... 5, 10, 20, 40, 80