Question

to what temperature a gas at 127 degree Celsius must be cooled so that its volume is reduced to one fourth of its initial volume pressure remains constant

Answer 1

It can be solved by using the relation of Charle's Law.
Charle's Law explains that: For a fixed mass of gas at constant pressure (P) ,the volume is directly proportional to the kelvin temperature (T). 

Mathematically, At constant P and Mass (or no. of moles = n)

V ∝ T

Or, T1 /T2 = V1 /V2........(1)
​Given that:
T1 = 127º​ C = (273 + 127) = 400 K
T2 = ?
Let V1 be 1 L
V2 would be 1/4 L
Using equation 1)
T2 = V2/V1 x T1
    =  1/4 x 400 K
   = 100 K
So the temperature should be reduced to 100 K to get the 1/4 of initial volume of gas.

Answer 2

T1=127°C=400K
T2=?
LET V1 be x
V2 =1/4x
according to charles law
V1/T1=V2/T2
V/400=1/4V×1/T2
T2=V/4×400/V
=100K
=-173°C