Let d and s be the cost of a double and single- occupancy room, respectively. Since a double-occupancy room cost $20 more than a single room, we can write
On the other hand, we know that 15 double-rooms and 26 single-rooms give $3088, then, we can write
Solving by substitution method.
In order to solve the above system, we can substitute equation (A) into equation (B) and get
By distributing the number 15 into the parentheses, we have
By collecting similar terms, it yields,
Now, by substracting 300 to both sides, we obtain
then, s is given by
In order to find d, we can substitute the above result into equation (A) and get
Therefore, the answer is: