Answer:45/32.
Step-by-step explanation:
51-6=45. Thus, our answer is 45/32.
Again, nice problem. These are not super easy. You need to imagine the triangles in the figure and relate sides.
For instance: ADC, its hypotenuse is 15
For ABC, it is 20,
so 20/15 is the ratio between both triangles. Now let's choose the side with 'x'
x is one side of ADC, the corresponding side in ABC is 15 (the second longest sides). You need to rotate the triangles, etc ... That's the tricky part :)
So:
20/15 =15/x ----> x = 15*15/20 = 225/20 = 45/4
Which is C
Not sure whether it's too late to help you though!!!!
Also notice that it's kind of a product rule:
x * 20 = 15 * 15
I am sure the book explains a short way of getting to this equation, like sides opposite, blah blah, but what i told you is the reason. You asked for understanding it! Best luck!
Answer:
680
Step-by-step explanation:
Use the binomial coefficient where you choose 
numbers out of 
possible numbers and find the total amount of combinations since order does not matter:
Thus, you can make 680 three-non-repeating-number codes
Answer:
35-7x
Step-by-step explanation:
Multiply parenthesis by -7
Answer:
-24
Step-by-step explanation:
-3 (x + 4) - 2 = -2 (x - 5)
-3x - 12 - 2 = -2x + 10
-3x + 2x = 10 + 12 + 2
-x = 24
x = -24
