A study took a group of adults and randomly divided them into two groups. One group was told to drink tea every night for a week, while the other group was told not to drink tea that week. Researchers then compared when each group fell asleep. Does this describe an observational research study or an experimental research study?

Marco has $38.43 dollars in his checking account. his checking account is linked to his amazon music account so he can buy music. the songs he purchases cost $1.29. part 1: write an expression to describe the amount of money in his checking account in relationship to the number of songs he purchases. part 2: describe what the variable represents in this situation.

If t8 = 4 and t12 = −2, find the first three terms of the arithmetic sequence.

The length of the line segment ac is 8x-9 what is the value of x