Using 7 four times and 1 one time getting to 100

Sole with work in 10 years, the average number of hours of tv watched per week by teenagers dropped from 23.9 to 21.4. find the percent of change.

Math i have no idea how to do a and b

Plz answer asap! i will reward brainliest and 12 points for these three questions!take notice: these three questions are completely different! 1) what is the percentage of sugar in the syrup made of 10 kg of water and 4 kg of suugar? 2) what was the original price if after 10% discount it became $450? 3) at first a price was decreased by 12%, then it was disounted again by an additional 5%. what is the percent of the total discount? , and remeber i will award brainliest and 12 points!