Okay, here we have this:
Considering the provided information, we are going to identify the equation, so we obtain the following:
If y varies directly with x then it means that x goes in the denominator of the function.
And let's determine by what value we have to multiply x so that y is 75 when x is 5:
y=kx
Replacing
75=k*5
k=75/5
k=15
Then, the function is: y=15x. And the correct answer is the first option.