Systems of equations
x+y+z=1 2x+4y+6z=2 -x+3y-5z=11

A20? -foot ladder is placed against a vertical wall of a? building, with the bottom of the ladder standing on level ground 19 feet from the base of the building. how high up the wall does the ladder? reach?

Evaluate cos2θ for cosθ = square root of 3/2

65% of students in your school participate in at least one after school activity. if there are 980 students in you school, how many do not participate in an after school activity?