So you know the ideal gas law 
PV = nRT 
well R is a constant, Pressure is given to be constant and of course the moles, n are constant. 
What is left is direct variation. 
Initial temp and volume
V = kT 
final temp and volume 
v = kt 
crate a ratio, I think this is called charles law 
V/v = T/t 
4 / 9.840 = 7.836x10 / t 
solve for final temp, will be in Celsius since T is in Celsius 
** round answer to 4 significant figures.. 
t = (78.36 * 9.84 ) / 4 
t = 192.8 C