A for Annie and B for Brian.
a = 5b +2
a+b = 20 hours.
This is a double variable question. The only way to solve it is to make the bottom equation have one variable. We can do this with the top equation. Substituting a for the top equation, you get 5b + 2 + b= 20. Simplifying this, you get 6b + 2 = 20. Subtract 2 from both sides, and you get 6b = 18. Divide both sides by six to get b = 3. We now know that Brian traveled 3 hours. Substitute 3 for b in the top equation, and you get 15 +2. Add them, and Annie traveled 17 hours. To check, substitute both numbers with the given values, and you get 20 hours. Hope this helps in any way, and have a nice day!