Perimeter of the trapezoid = a + c + 2b
58 = a + c + 2b
Average of bases = (a + c)/2
19 = (a + c)/2
a + c = 38
Substituting (a + c) into the first equation:
58 = 38 + 2b
b = 10 in
We also know that:
c = 2b + 7
c = 2(10) + 7
c = 27 in
a + 27 = 38
a = 11 in
a = 11 in; b = 10 in; c = 27 in