Two lines are parallel when their slopes are the same.
Answer:
- digits used once: 12
- repeated digits: 128
Step-by-step explanation:
In order for a number to be divisible by 4, its last two digits must be divisible by 4. This will be the case if either of these conditions holds:
- the ones digit is an even multiple of 2, and the tens digit is even
- the ones digit is an odd multiple of 2, and the tens digit is odd.
We must count the ways these conditions can be met with the given digits.
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Since we only have even numbers to work with, the ones digit must be an even multiple of 2: 4 or 8. (The tens digit cannot be odd.) The digits 4 and 8 comprise half of the available digits, so half of all possible numbers made from these digits will be divisible by 4.
<h3>digits used once</h3>
If the numbers must use each digit exactly once, there will be 4! = 24 of them. 24/2 = 12 of these 4-digit numbers will be divisible by 4.
<h3>repeated digits</h3>
Each of the four digits can have any of four values, so there will be 4^4 = 256 possible 4-digit numbers. Of these, 256/2 = 128 will be divisible by 4.
Answer:B.
Step-by-step explanation: I took the same class
Let x be the number of racing bikes, and let y be the number of mountain bikes.
1) 140x + 110y = 26150
2) 180x + 120y = 31800
Solve for one of the variables and plug that in to the other equation:
From equation 1: 140x = 26150 - 110y
x = (26150-110y)/140
Plug this into equation 2:
180((26150-110y)/140) = 31800
Solve for y, and find that y = 85 (the number of mountain bikes).
Plug that y into either equation to find x:
140x + 110(85) = 26150
x = 120 (the number of racing bikes).
So the answer is: 120 racing bikes and 85 mountain bikes.
