Answer: the cost of 1 one-inch binder is $4
the cost of 1 three-inch binder is $7
Step-by-step explanation:
Let x represent the cost of 1 one-inch binder.
Let x represent the cost of 1 three-inch binder.
Jesse selected 3 one-inch binders and 3 two-inch binders, which cost a total of $33. This means that
3x + 3y = 33 - - - - - - - - - - 1
Luann selected 2 one-inch binders and 1 two-inch binder, which cost a total of $15. This means that
2x + y = 15 - - - - - - - - - - - 2
Multiplying equation 1 by 2 and equation 2 by 3, it becomes
6x + 6y = 66
6x + 3y = 45
Subtracting, it becomes
3y = 21
y = 21/3 = 7
Substituting y = 7 into equation 2, it becomes
2x + 7 = 15
2x = 15 - 7 = 8
x = 8/2 = 4
