800,000 rounded to the nearest hundred thousand

Solve the problem by making up an equation. a child is 12 years old, and his father is 32 years older. in how many years will the age of the father be 3 times the age of the child?

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?

At noon a tank contained 10cm water. after several hours it contained 7cm of water. what is the percent decrease of water in the tank?