How do you make calculations with percents

Fred has a spinner that is split into four equal sections: red, blue, green, and yellow. fred spun the spinner 688 times. which of the following would be a good estimate of the number of times the spinner lands on the green section? a. 269 b. 603 c. 344 d. 189

In a singing competition, there are 150 participants. at the end of each round, 40% of the participants are eliminated. how many participants are left after n rounds?

Andy has $310 in his account. each week, w, he withdraws $30 for his expenses. which expression could be used if he wanted to find out how much money he had left after 8 weeks?