Answer:
See below ~
Explanation:
The perimeter of a figure refers to the sum of the side lengths of its edges.
Figure (a) : Triangle
⇒ P = 2a + 1 + 3a + a - 4
⇒ P = 6a - 3
⇒ P = 3 (2a - 1)
Figure (b) : Hexagon
⇒ P = 3m - 1 + 3n + n + m + 3m + 1 + 4n + m + n + 2
⇒ P = 3m + m + 3m + m + 3n + n + 4n + n + 1 - 1 + 2
⇒ P = 8m + 9n + 2
Figure (c) : Trapezoid
⇒ P = 2a + 3 + 3a - b + 2a + 2b - 4 + b + 4
⇒ P = 2a + 3a + 2a + 2b + b - b + 4 - 4 + 3
⇒ P = 7a + 2b + 3