Math question for college student

Question

The sum of lengths of any two sides of a triangle must be greater than the third side. If a triangle has one side that is 21 cm and a second side that is 3 cm less than twice the third size, what are the possible lengths for the second and third sides?

Answer 1

x=2y-3

x+y>21

3y-3>21

3y> 24

y>8 cm

x>13 cm

x-y<21

2y-3-y<21

y<24

x<45

13<x<45

8<y<24