Answer:
C
Step-by-step explanation:
 
        
             
        
        
        
Answer:
y = 3
x = 2
Step-by-step explanation:
-5x + 4y = 2 
 9x - 4y = 6
Sum both eq.
-5x + 9x = 4x
+4y - 4y = 0
2 + 6 = 8
then:
4x + 0 = 8
4x = 8
x = 8/4
x = 2
from the first eq.
-5x + 4y = 2
-5*2 + 4y = 2
-10 + 4y = 2
4y = 2 + 10
4y = 12
y = 12/4
y = 3
Check:
from the second eq.
9x - 4y = 6
9*2 - 4*3 = 6
18 - 12 = 6
 
        
             
        
        
        
Answer:
A
Step-by-step explanation:
 
        
                    
             
        
        
        
Answer:
2
Step-by-step explanation:
 
        
             
        
        
        
77 unicorns, because yesterday the ratio was 6:5 and today it is 3:4. If you add the numbers for both ratios together, you get 11 and 7. Finding the LCM of these two gives 77 (because 7 and 11 are both prime). 
You find the LCM of the sums because when you find values based on ratios, you divide value by the sum of the ratio. 
e.g. I have 100 fruits. The ratio of apples to oranges is 2:3. How many apples are there?
To solve this you'd add 2 and 3 (5), divide 100 by 5 (20), multiply that by 2 (40) because that's the ratio of apples to oranges. 
In this case, you do the reverse. So If I have 77 unicorns, then yesterday there were (77/11 = 7, 7*6= 42, 7*5= 35) 42 green unicorns and 35 yellow. The sum of 42 and 35 is 77. If you do this process with the other ratio you'll get similar results as well.