Answer:
the answer is d.
Step-by-step explanation:
 
        
             
        
        
        
Hope this is what you where looking for
 
        
        
        
To get 10% of 40, you move the decimal point one way to the left. So 10% of 40 is 4
Now you need 2% and because you know 10% is 4, you divide that by 10 and multiply it by 2 because of the 2%
4/10=.4 .4•2=.8
Now you add them
4+.8=4.8 
12% of 40 is 4.8
        
             
        
        
        
Answer:
Step-by-step explanation:
Let the number of blue marbles be x
The number of green marbles = 3x - 2
Total marbles= 18
x + 3x -2 = 18
4x - 2 = 18
      4x = 18+2
       4x = 20
x =20/4
x =5
 The number of blue marbles = 5
The number of green marbles = 3*5 - 2 = 15 -2 = 13