It's too short. Write at least 20 characters to explain it well.
The range I think it should be [0,infinity)
The first thing we must do for this case is to define variables.
We have then:
x = cost of a hardcover book
y = cost of a paperback book
We write the system of equations:
3x + 7y = 29.50
2x + 5y = 20.50
The solution to the system is:
x = 4 $
y = 2.5 $
Answer:
the cost of a hardcover book is $ 4
The rate of change is given as 10 per day--the number of cans the class plans to bring each day.
After 10 days at that rate, the change will be 10*10 = 100. Since the total after 10 days is 205, we compute the initial value as 205 -100 = 105. This is the number the teacher already had.
cans = 10*days +105
