Please help! Correct answer only! I've been on this question for more than an hour...

You pick a card at random. Without putting the first card back, you pick a second card at random.

What is the probability of picking a 3 and then picking a 3?

Simplify your answer and write it as a fraction or whole number.

What is the value of 1/3× + 7x, when x =5

Initially 100 milligrams of a radioactive substance was present. after 6 hours the mass had decreased by 4%. if the rate of decay is proportional to the amount of the substance present at time t, find the amount remaining after 24 hours. (round your answer to one decimal place.)

The swimming pool is open when the high temperature is higher than 20∘c. lainey tried to swim on monday and thursday (which was 33 days later). the pool was open on monday, but it was closed on thursday. the high temperature was 30 ∘c on monday, but decreased at a constant rate in the next 33 days. write an inequality to determine the rate of temperature decrease in degrees celsius per day, d, from monday to thursday.