I'm not exactly sure what you need to find so I'll just put this:
If you need to find the area:
A = l x 2
A = 11 x 7.7
A = 84.7 cm^2
If you need to find the perimeter:
P = 2(l + w)
P = 2(11 + 7.7)
P = 22 + 15.4
P = 37.4 cm
Note: It's okay to ask for help when you need it, even if your task is easy! :)