Find the difference for (-8ab+7a-+2)

Given this information, which expression must represent the value of b?

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?

If f(x) =3x-2 and g(x) =2x+1 fins (f+ g) (x)