For what values of x is the quantity x−9 negative?

What value of x is in the solution set of 4x - 12 s 16 + 8x? -10 -9 -8 -7

How many kilograms of a 5% salt solution and how many kilograms of a 15% salt solution must be mixed together to make 45kg of an 8% salt solution?

Two years ago a man was six times as old as his daughter. in 18 years he will be twice as old as his daughter. determine their present ages.