It would be 48 bc if you add it all up and subtract it and add again and multiply and divide and multiply within a and the substance of present after 6 yr you will see that i have wasted your time and that is not the answer
        
             
        
        
        
Answer:
The answer to your question is 
a) Poster              width = 3 in
                             lenght = 9 in
b) banner 
                            width = 2 in
                            lenght = 10 in
Step-by-step explanation:
a) For the poster
    width = x
    lenght = 3x
Perimeter of a rectangle = 2base + 2 height
                                          = 2(x) + 2(3x) = 24
                                          2x + 6x = 24
                                          8x = 24
                                            x = 24/8
                                            x = 3
      width = 3 in
      lenght = 3(3) = 9 in
b) For the banner
     width = y
     lenght = 5y
Perimeter of a banner = 2 base + 2 height
                                         2 (y) + 2(5y) = 24
                                         2y + 10y = 24
                                         12y = 24
                                            y = 24/12
                                            y = 2
      width = 2 in
      lenght = 5(2) = 10 in
 
        
             
        
        
        
their relative speed is 4 mph. so we put 
4 mph = (25 mi)/x => x=25/4.