The parts of the sum are 55 and 80.
Step-by-step explanation:
Let,
'x' be the smaller part and
'y' be the greater part of the number.
The sum is x+y = 135. --------(1)
The greater part y = x+25. ---------(2)
Substitute (2) in (1),
⇒ x+(x+25) = 135
⇒ 2x+25 = 135
⇒ 2x = 110
⇒ x= 110/2
x = 55
The smaller part is 55.
Substitute x=55 in (2)
y = 55+25 = 80
The greater part is 80.