Explanation: First, let's first out how much 4 pairs of sandals would cost. Well, we know that 4 pairs of sandals and a pair of boots cost $109.95 altogether, and the boots itself cost $29.99, we want to subtract the boots out of the equation. So 109.95 - 29.99 = 79.96. Now we know that $76.96 represents the cost of 4 sandals. To find the cost of 1 sandal, we would divide 76.96 by 4, which is 19.99. Therefore, 1 pair of sandals costs $19.99