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Answer:
1. Calculate the sum of "a", "b" and "c".
2. The perimeter equation is: 
Step-by-step explanation:
In this case, P denotes the triangle's perimeter while a, b, and c are the triangle's sides.
The definition states that the sum results from an addition operation. Thus, the statement "The perimeter P of a triangle equals the total of sides a, b, and c" means that the perimeter is determined by aggregating the lengths of the triangle's sides.
Consequently, you can express this in the following equation:

Part 1) side 1=15'-7" side 2=20'-4" side 3=26'-2" To determine the total length of all three sides, add them together: total length=side 1+side 2 +side 3. By substituting, total length=15'-7"+20'-4"+26'-2" can be expressed as total length=(15'+20'+26')+(7"+4"+2"). This simplifies to total length=(61')+(13"). Keep in mind that 12"=1', so 13" can be expressed as 12"+1"=1'+1". By substituting again: total length=(61')+(1'+1") simplifies to total length=(62')+(1") which leads to 62'-1". Therefore, the total length of the three sides is 62'-1".