Janelle is making a poster. she cuts a triangle out of poster board. what is the area of the poster board that she has left?

The poster is a parallelogram, and it's area is:

A = bh

A = 20 x 10

A = 200 in.^2

Note: ^2 after in. means squared for area.

The area of the triangle that Janelle cut out of the poster board is:

A = 1/2bh

A = 1/2 x 10 x 9

A = 90/2

A = 45 in.^2

The area of the poster board that she has left is: 200 - 45 = 155 in.^2

155 in.

Step-by-step explanation: