Let b be the price of the bath towels and h be price of the hand towels. For Helen, we can write the following equation
And for Althea, we have
Then, we have 2 equations in 2 unknowns. By multipliying the first equation by -2, we have the following equivalent system of equation
By adding both equations, we have
Then, b is given by
Therefore, 1 bath towel cost $12, which corresponds to option 3