Answer:
a=5, b=10, c=11
Step-by-step explanation:
a= shortest side
b= "third" side
c= longest side
Equations:
c=6+a
b=2a
a+b+c=26
so we can see there is a in all of the equations, so we can plug all of them into the equation for the perimeter
a+(2a)+(6+a)=26-->4a=20-->a=5
with a, we can plug that into the equations to get b and c
c=6+a-->6+(5)-->c=11
b=2a-->b=2(5)--> b=10