We can solve this by setting up 2 equations. We can use any letters like. For now, I'll use x and y.
So now we know that x - y = 0.7 and x + y = 1.
Now we can eliminate one of the letters by adding or subtracting one equation from the other. I am going to eliminate y by adding the two together (the y and the -y cancel).
This gives us 2x = 1.7, and so x = 1.7 ÷ 2 = 0.85
Finally, we can substitute x for 0.85 back into one of the original equations to figure out what y equals. I'm going to use x + y = 1.
So now we have 0.85 + y = 1, so y = 1 - 0.85 = 0.15
The numbers, therefore, are 0.85 and 0.15 (you can check by using the other equation).
Hope this helps!
Im pretty sure its A, but dont count on me!!! i hope it helps :/
Answer:
Step-by-step explanation:
Let x represent the number of calls made with plan 1 in a month.
Let y represent the number of calls made with plan 2 in a month.
Plan 1 charges $25 per month for unlimited calls. This means that the total cost of x calls made with plan 1 in a month would be $25
Plan 2 charges $15 per month plus $0.04 per call. This means that the total cost of x calls made with plan 1 in a month would be
15 + 0.04x
a) for the number of calls for which Plan 1 is more economical than Plan B, it becomes
25 < 15 + 0.04x
25 - 15 < 0.04x
10 < 0.04x
0.04x > 10
x > 10/0.04
x > 250
b) plan 1 would be more economical when the calls per month exceed 250.
