Hi guest!

It would be really helpful if you inserted the image...

Well anyways, let's get started.

To find surface area, we have to calculate the area of all sides and add them up.

Let's start off by finding the surface area to the triangle with legs of 12 and 9.

The area of a triangle is b*h/2

So, the area is (12*9)/2=54

Now we can find the other triangle's area.

(12*5)/2=30

So, the triangle's face is 54+30=84 cm. We know that there is an identical triangle on the back too, so we multiply 84 by 2, 84*2=168.

Now let's find the area of the bottom of the prism.

It's just a rectangle with side lengths of 20 and 5+9=14.

So, the area is 20*14=280.

Lastly, let's find the area of the right side of the prism.

It is just a rectangle with side lengths of 20 and 15.

The area is 20*15=300

Finally let's find the area of the left side of the prism.

Again, it's just another rectangle with side lengths of 20 and 13.

The area is 20*13=260

Now, all we have to do is add it all up!

168+280+300+260= 1008.

I hope this helped you, guest!

:)