Help ASAP PLEASE I really need help with this

Which expression calculates the speed in meters per second of an object that travels a distance of 100 m every 20 seconds

On a piece of paper graph f(x)=5•(0.4)^x

Graph red beads cost $1 an ounce and gold beads cost $3 an ounce. juanita wants to purchase a 12-ounce mixture of red and gold beads that she can sell for $2 an ounce. the solution of the system shows the number of beads needed for juanita to break even. x + y = 12, x + 3y = 24 how many ounces of red beads will juanita buy to break even? how many ounces of gold beads will she buy?