Find are of base just please give me a formula

Since I'm not sure what shape you need I will give you these.

Triangle

1⁄2 b*h

b=base

h=height

b=base     h =height

Rectangle

length * width

Trapezoid

1⁄2 h ( b_1+ b_2 )

h = height

b_1=base 1

b_2=base 2

Square

s^2 s =side

Parallelogram

base * altitude

Pentagon

1⁄2  a*p  

a = apothem

P = perimeter

Hexagon

1⁄2  a*p  

a = apothem

P = perimeter

Heptagon

1⁄2  a*p  

a = apothem

P = perimeter

Octagon

1⁄2  a*p  

a = apothem

P = perimeter

Hope this helped you! I would appreciate a brainliest!

step-by-step explanation:

341

step-by-step explanation:

all you have to do is 9x31 (which equals 279) and then 20x31 (which equals 620). then you have to subtract. 620-279=341.