Helium was heated in a sealed container from 18°C to 36°C. The original pressure of helium was 0.84 atm. Find the new pressure assuming V and n remain the same.

I put 0.84 over 18 and set it equal to x over 36. I got 1.7 atm but it says its wrong?

Use (P1/T1) = (P2/T2). You assumed that doubling the T would double the P. It works that way but you must use the right T. You may not use T in C; convert to kelvin.

K = 273 + C