During a sale, the price of a sweater was changed from $20 to $16. What was the percent of decrease in the price of the sweater? Possible Answers:
A. 40%
B. 25%
C. 20%
D. %4

How many 3-digit numbers can you write using only digits 1 and 7? (of course, digits can repeat.) how many 3-digit numbers can you write using only digits 1 and 7? (of course, digits can repeat.)

Marco states that 7.696696669…… is a rational number because it is a repeating decimal. is he correct? justify your answer.

Me with these questions , i don’t understand scientific notation!