In ΔCDE, m∠C = (7x-15)^{\circ}(7x−15)
∘
, m∠D = (3x+6)^{\circ}(3x+6)
∘
, and m∠E = (x+2)^{\circ}(x+2)
∘
. Find m∠D.

2500

step-by-step explanation:

"image"

step-by-step explanation:

in most of these problems, the notation is that the point with a "prime" is the image of the point without. that is, b' is the image of b.

here, there is no dilation or reflection. there is simply translation (with no direction shown). which figure you call the "preimage" and which one you call the "image" is up to you. as a matter of convention, the naming is as described above.

ca = ec

cpctc makes it so that corresponding parts of the triangle you proved to be equal are equal, the other options aren't part of the part of the triangles you proved to be equal.