Answer:
a = 9
Explanation:
this shape is an isosceles trapezoid where the pair of non-parallel sides are equal; therefore we can set up this equation to find 'a'
P = a + a + 2 + 8
28 = 2a + 10
18 = 2a
a = 9
Check:
9(2) + 2 + 8 = 28
18 + 10 = 28
28 = 28