A+B+C+D+E=540°
4X+5+7X+6X+10+5X-5+4X+10=540
26X = 520
X = 520 : 26 = 20°
E = 4X + 10 = 80 + 10 = 90 °
44 the total volume of this composite solid is 896
A way to add fractions that always works is to multiply each numerator by the denominator of the other, then express the sum of products over the product of the denominators.

Here, you have
The sum is -1 1/12
The answer for both of these would be a rectangle.
A rectangular prism has 6 faces, all of which are rectangles. Slicing the prism parallel to any of the faces, whether they are end faces or bases, will result in a rectangular cross-section.
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