Question 328811
p=a+b+c
b=2a+1
c=3a-1
42=a+2a+1+3a-1
42=6a
6a=42
a=42/6
a=7 ans. for the first side.
b=2*7+1=14+1=15 ans. for the second side.
c=3*7-1=21-1=20 ans. for the third side.
Proof:
7+15+20=42
42=42