Aballoon with a volume of 1.50 l is put in liquid nitrogen (temperature is –195.8 ºc, 77.2 k), shrinking its volume to 0.40 l. in kelvins, what was the balloon’s original temperature?
a)46.0 k
b)85.0 k
c)220 k
d)290 k

According to Charles law, we know, at constant pressure, volume is directly proportional to temperature. 
So, V/T = constant 

V₁/t₁ = V₂/t₂
V₁t₂ = V₂t₁

Here, we have: V₁ = 1.50 L
V₂ = 0.40 L
T₂ = 77.2 K
T₁ = ?

Substitute their values into the expression:
1.50 × 77.2 = 0.40 × T₁ 
T₁ = 115.8 / 0.40
T₁ = 289.5
After rounding-off to unit place value, it would be equal to 290 K

So, In short Option D would be your correct answer.

Hope this helps!

Inner peace.. jk it's  a stable electron configuration