ElectricPavlov

Volume of larger cube  10 * 10 * 10 = 1000 cm^3

Volume of a smaller cube   2 * 2 * 2 = 8 cm^2               1000/8 = 125 smaller cubes

Surface area of large cube = 10*10 * 6 = 600 cm^2

                        smaller cube = 2 * 2 * 6 = 24 cm^2    

                                                                 and there is 125 of them , so total surface area = 125 * 24 = 3000 cm^2

600 / 3000 = 1/5

You are looking for the time at which they will both be the same distance

rate X time = distance  

for the first runner   distance = 25 miles + 7.5 m/hr * x        where x is the time in hours

   theis equals the total distance for the second runner    23  miles + 8.3 m/hr * x

25 + 7.5 x    =   23 + 8.3 x       solve for x  (  in hours)  when they will be at the same distance .....

1/2 c   =   43 + 1/3 d

c = 86+ 2/3 d  

c+ d = 821

(86+ 2/3 d )  + d = 821

                5/3 d   = 735

                       d = 441         then   c = 380

Mising important info in your question......

Can you be more specific?

Arrange given line to y = mx+b form   where m = slope

y = 2x -2    slope = 2   parallel slope is the same = 2

y = mx +b

y = 2x + b     sub in the point given to calculate 'b'

10 = 2(1) + b

b = 8

y = 2x + 8

25 + 7.5 x    =   23 + 8.3 x       solve for x  ( hours)

Acceleration is change in velocity over change in time

28 m/s  /   4 sec =   7 m /s²

x^2 + 8x +4      Multiply by 1.75

1.75 x^2 +  14 x + 7

Use distance formula

d^2 = 800    

800 = ( x-7)^2 + ( 21-4)^2

800 = x^2 -14x+49 + 289    

x^2  - 14x -462 = 0       <=======  Now use Quadratic Formula to solve for 'x'