Answer: 3.64, 10.00
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Answer: 2/20, because all those marbles in total is 100. the blue and black marbles would be 70, if you simplify all of it it'd be 2/25.
Step-by-step explanation:
 
        
             
        
        
        
Answer:
After solve the equations we get value of k=3
Step-by-step explanation:
We need to find value of k for which the lines x+2y=0, 3x-4y-10=0 and 5x+ky-7=0 are concurrent.
If the lines are concurrent, they pass through same point.
Let:

First solving equation 1 and 2 to find values of x and y
From eq(1) we find value of x and put it in eq(2)

After solving we get value of y=-1
Now putting in eq(1) to get value of x

So, Value of x= 2
Now put value of x=2 and y=-1 into eq(3) to find value of k

So, After solve the equations we get value of k=3