Question

two sides of triangle are 20cm and 35 cm the perimeter of triangle is 80 cm find the third side​

Answer 1

we know
perimeter of triangle is sum of all sides so
20+35+x=80
(let the third side be x)
55+x=80
x=80-55
x=25
so third side is 25cm

Answer 2

Given, that the perimeter of the ∆ is 80 cm

perimeter =the sum of all three sides

Side 1 =20
Side 2=35
Side 3 = 'x'

Therefore....., 20 +35 + X = 80
35+20 =55

X = 80 - 55
X = 25 cm

The measurement of the third side is 25cm