Answer:
CD = 18
Explanation:
find the semiperiter (1/2 perimeter or L+W)
80 : 2 = 40
now we know that 4z + 2 + 3z + 3 = 40
we solve for z with an equation
4z + 2 + 3z + 3 = 40
7z = 40 - 2 - 3
7z = 35
z = 35 : 7
z = 5
now we find CD
3z + 3 = (z=5)
3 * 5 + 3 =
15 + 3 =
18
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check (remember pemdas)
4z + 2 + 3z + 3 = 40
4*5+2+3*5+3 = 40
20+2+15+3=40
40 = 40
the answer is good