Answer:
15.96atm
Explanation
According to general gas equation
P1V1/T1 = P2V2/T2
P1 and P2 are  pressures
V1 and V2 are the volumes
T1 and T2 are the temperatures
Given
P2 = 2.00atm
V1 = 18.8L
v2 = 300l
t1 = 200k
T2 = 400K
Required
P1 = ?
Substitute
P1 =P2V2T1/T2 V1
P1 = 2 * 300*200/400*18.8
P1 = 120000/7520
P1 = 15.96atm'
Hence the original pressure is 15.96atm