X = velocity of plane 
 y = velocity of wind 
 x - y = 1680/5 = 336 mph .....(1) [ plane flying against the wind] 
& 
 x + y = 1680/4 = 420 mph....(2) [ plane flying with the wind] 
 Adding (1) and (2) to eliminate y gives 
 2x = 756 
 x = 378 mph is the speed of the plane with no wind.
        
                    
             
        
        
        
Answer:
y = 60x + 22 
262 miles
Step-by-step explanation:
Given that the car enters the turnpike at 22 miles, his initial starting point, or initial value (b) is 22.  You also know the rate at which the car travels is 60 miles per hour, which is the slope (m).  Using the slope-intercept formula of a linear function: y = mx + b, you can plug in your initial value and rate: 
y = 60x + 22, where y = the total miles and x = the number of hours traveled 
After 4 hours: 
y = 60(4) + 22 = 240 + 22 = 262 miles 
 
        
             
        
        
        
14.25+2.30=16.55     so, dr spent $16.55 on school supplies
        
                    
             
        
        
        
Step-by-step explanation:
-1,355= -1355/1000
-1,352= -1352/1000