Annie traveled 5 times the sum of the numbers fo hours Brian traveled and 2.
We use "a" for the hours Annie traveled and "b" for the hours Brian traveled.
Therefore, a = 5b + 2 ( 5 times Brian's hours is 5b)
The total of hours they traveled is 20.
Therefore, a + b = 20
Now, both of those equations have 2 unknowns ( a and b), so we cannot solve
them by themselves.
But if we combine them to form an equation with only one unknown, then we
can solve that.
So, if a = 5b + 2 and a + b = 20, we can substitute the a in the second equation
with what a equals in the first (5b + 2), and we get...
5b + 2 +b = 20 | combine like terms
6b + 2 = 20 | -2
6b = 18 | /6
b = 3
There for Brian travels 3 hours and Annie 17 ( 3 x 5 + 2 or 20 - 3).
