Answer:

Step-by-step explanation:
Given that,
y varies directly as x. It means,
y = kx
Where
k is the constant of variation
or

So, the constant of variation is
.
Answer:
The correct answer will be:

Step-by-step explanation:
It is given that :
Initial temperature, 
Final temperature,

Time taken :

Change in temperature per hour:

Putting the values of temperatures and time:

The error done by Wen was during calculating the values of fraction.
So, the correct answer is :
instead of