How many times in the 30 minutes graphed is the temperature exactly 40 degrees? (Brainlist!!)

Select all the correct answers. what is 221,000,000,000,000,000,000 expressed in scientific notation?

The train station clock runs too fast and gains 5 minutes every 10 days. how many minutes and seconds will it have gained at the end of 9 days?

Write an algebraic expression to match each statement a. four less than 8 times a number b. twice the difference of a number and six c. nine from a number squared