Subtract the values using elimination method -9a-3b-39 4a+2b-4

What properties allow transformation to be used as a problem solving tool

Aladder that is 20ft long is leaning against the side of a building. if the angle formed between the ladder and the ground is 75 degrees how far is the bottom of the from the base of the building?

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.