Step-by-step explanation:
We are told that a notebook costs $3.50 and a binder costs $6.70
If we represent the number of notebooks to be n and binders to be m
Also, we are told that she bought 4 fewer notebooks than binders
Then, we can say that
The total amount spent can be obtained using the basic principle
Therefore
we have
But, we have established that n = m-4
Thus
The total amount in terms of the binders will be
Thus,
we can also express the total amount in terms of the binders as