Equivalent combination for 2x +7 + 5x+4-x

Find the area of the triangle formed by the origin and the points of intersection of parabolas y=−3x^2+20 and y=x^2−16.

60 musicians applied for a job at a music school. 14 of the musicians play both guitar and drums, 28 play drums, 18 play the guitar. what is the probability that the applicant who gets the job plays drums or guitar?

Isaac wants the equation below to have no solution when the missing number is placed in the box. which number should he place in the box?