4(2a - 1) in expanded form

A + b = 20
a = 5(b + 2) = 5b + 10

5b + 10 + b = 20
6b + 10 = 20
6b = 20 - 10
6b = 10
b = 10/6
b = 1 2/3 hrs

a = 5b + 10
a = 5(10/6) + 10
a = 50/6 + 10
a = 50/6 + 60/6
a = 110/6
a = 18 1/3 hrs

check..
a + b = 20
110/6 + 10/6 = 20
120/6 = 20
20 = 20 (correct)

so Annie (a) traveled 110/6 hrs (or 18 1/3 hrs) and Brian (b) traveled 
10/6 hrs (or 1 2/3 hrs)