How do you write 40% as a decimal?

Which ordered pair (c, d) is a solution to the given system of linear equations- c+2d=13 -9c-4d=-15

Tom can paint the fence in 12 hours, but if he works together with a friend they can finish the job in 8 hours. how long would it take for his friend to paint this fence alone?

Solve the equation: x - 9 = -6 + 5 a. 21 b. 7 c. 14 d. 2