Physics question - resistance and power

Hi I am stuck on this Isaac physics question. QUESTION AT BOTTOM.
I did 1/R + 1/4R to get 5/4R which = 1/Req.
So Req = 4R/5
Then used P = V^2/R and got the answer P = 5V^2/4R
However Isaac physics says this is wrong.
QUESTION:
The figure below shows a simple circuit diagram with two resistors in a parallel arrangement, connected to an ideal battery.
Circuit diagram showing two resistors of resistance R1 and R2 in parallel with a cell of voltage V.
Figure 1
Circuit diagram of two resistors in parallel.
If R 1 =R and R 2=4R , what is the total power dissipated in the two resistors, in terms of V and R.

Your answer of 5V^2/4R is correct, as I have done this question and got it correct with that answer. It might be that you've typed it in a format it doesn't like. Try to copy and paste this into the answer box:
(5*V**(2))/(4*R)