Answer:
Step-by-step explanation:
Are u stupid?
 
        
             
        
        
        
You do inverse op
2.7+23.5=26.2
        
                    
             
        
        
        
190mph 
I used speed calculator with advanced mode 
HTTP://www.omnicalculator.com/everyday-life/speed
 
        
             
        
        
        
Step-by-step:
Use slope formula to find the slope. (y - y)/(x - x)
Make sure the x and y in front of the minus is a pair that goes together, as well as the x and y behind the minus sign. So 
8 - -4 goes on top, that's 12
0 - -1 goes under, thats 1
12/1 is the slope which is just 12. Use either point to fill in the second x and the second y in the point-slope equation. m is the slope.
y - y = m(x - x)
y - 8 = 12(x - 0)
y - 8 = 12x
 
        
             
        
        
        
Must do multiplication first....
-2/5 - 3/7 x 7/10
-2/5 - 21/70 (I'll reduce 21/70)
-2/5 - 3/10
Now you have to find a common denominator and subtract
-35/50 = -7/10......is what I get