Answer: length when perimeter is 78 units: a=26 ,b=13
Length when perimeter is 156 units:
a=26 , b=52
Step-by-step explanation: Given one side =26 , the other is twice as long
Perimeter of a parallelogram =2(a+b)
Using perimeter=78= 2(26+b)
78=52+2b
78-52=2b
26=2b
b=26/2
b=13
When perimeter is 78 units a=26,b=13
Using perimeter =156 units
156=2(26+b)
156=52+2b
156-52=2b
104=2b
b=104/2
b=52