Am I correctly calculating the density altitude? I came across the following question while studying for the FAA PPL written test:

Determine the density altitude for these conditions:
Altimeter setting: 30.35
Runway temperature: +25°F
Airport elevation: 3,894 ft. MSL

I performed the following steps:
Temperature (°C) $\color{red}{= 5/9 × 25} = 14 $
Pressure altitude (PA) $= 3,894 + (29.92-30.35) × 930 = 3494 $
Density altitude (DA) $= \text{PA} + 120(14 - 15 + .002×\text{PA}) = 4200 $
Yet that answer is not listed, and according to the DA/PA graph provided, DA is 2000ft.
My final formula seems to be correct according to Wikipedia, plus it also matches my intuition of how PA works: According to the question we have 14°C at 4000ft, as opposed to the expected 7°C at 4000ft; seeing as temperature is higher, DA should be higher than PA.
Where am I going wrong?
Check your temperature conversion: 25F is -3.9C...

Should be (25-32)*(5/9).