You just study alot and do questions on fractions
        
             
        
        
        
Answer:
Finding the mean is very simple, add them all together and divide that sum by the number of data points you have; in this case there are 45
Step-by-step explanation:
 = mean
 = mean
 
        
                    
             
        
        
        
Answer: Ax+By=C, y=kx
Step-by-step explanation:
Ax+By=C is the standard form of a line. 
y=kx is a proportional line, which is just a linear equation without the intercept.