Im trying to do this question
is directly proportional to and when . Find the value of when
Now put 147 into the formulae with
Answer book says 39, how?
The problem says it is directly proportional so:
if it were inversely proportional it would be y=k/x as you wrote.
Now if you calculate as you were doing but with the above correction you will arrive to k=3 and eventually you will obtain y=39 for x=13