solution is (4, - 7 )
given the equations
y = 2x - 15 → (1)
4x + 3y = - 5 → (2)
substitute y = 2x - 15 into (2)
4x + 3(2x - 15) = - 5
4x + 6x - 45 = - 5
10x - 45 = - 5 ( add 45 to both sides )
10x = 40 ( divide both sides by 10 )
x = 4
substitute x = 4 into (1) for corresponding value of y
y = (2 × 4 ) - 15 = 8 - 15 = - 7
solution is (4, - 7 )
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: