Answer:
 -4
Step-by-step explanation:
Parallel lines have the same slope
 -4
 
        
                    
             
        
        
        
Slope = 4/5 because the formula for slope is rise/run. count the x and y units point one and point two are away from each other.
        
             
        
        
        
Hi there! 
Your question: 
8.5 + 49(1-2.5k)=24.5
My answer: 
8.5 + 4(1-2.5k) = 24.5 >>>>>>> first, you have to distribute
8.5 + 4 - 10k = 24.5 >>>>>>>> now, we are going to combine like terms.
12.5 - 10k = 24.5 >>>>>> now, we are going to subtract 12.5 on both sides 
-10k = 12 >>>>>>>>> finally, divide -10 on both sides
k = -1.2
Hope this helps you!