Answer:
The fourth line will have 15 marbles
Step-by-step explanation:
The third line has 7 marbles. So, you double that and add one in order to find the number of marbles in the fourth line.
7*2=14
14+1=15
 
        
             
        
        
        
648-259= 389
There are 259 boys and 389 girls.
        
             
        
        
        
2/3 of the job was completed in 4 minutes. the job left will be completed in 2 minutes
 
        
             
        
        
        
Answer:
3.69 mm
Step-by-step explanation:
So it's a right triangle so you can use a^2+b^2=c^2
Plugging in what we know the equation becomes:
 2.8^2+2.4^2=c^2 (C = x because x is the hypotenuse)
7.84+5.76=c^2
13.6=c^2
The square root of 3.68782 which rounds to 3.69 
So x=3.69mm