If x is a rational number and y is the opposite of x, why do x and y have the same absolute value

Which of the following is the best first step in solving the equation below? 4+2㏒³x=17

Campus rentals rents 2 and 3 bedrooms apartments for $700 ans $900 a month respectively. last month they had six vacant apartments and reported $4600 in lost rent. how many of each type of apartment were vacant?

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?