Answer:
31.205
Step-by-step explanation:
The perimeter is the sum of the side lengths:
8.73 +12.4 +10.075 = 31.205
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If you're after an answer that has the appropriate precision (assuming these are measured values), that would be one that is rounded to 1 decimal place: 31.2.
The value of x is
-4x + 8 = 42
-4x = 42 -8
-4x = 34
x = -8,5
The correct answer is 14.
