Answer: 1100
Step-by-step explanation: mark x for the total sum.
0.35x+ 0.20x + 495 = x. 495= x-0.35x-0.20x
495= 0.45x. X= 495/0.45
Surface area is just the area of all these 4 triangles plus the rectangle.
First we can find the area of the rectangle.

Half of the length is 28 cm, so the full length must be 28 * 2 = 56 cm.


The base for the left and right triangles are 27. The heights would be the net length minus half the length of the rectangle:

Calculate the area:



We have two of these triangles.

Now do the other two pair of triangles. The bases for them are 28 + 28 = 56 cm. The heights would be the net width minus the width of the rectangle:

Now find the area:



We have two of these triangles.

Add all the areas together:
3 because 4×3=12 and if you divide12÷3/4 it helps you check