Answer:
Total # of marbles: 10
# of red marbles: 7
Probability of choosing a red marble out of 10 marbles: 7/10
Then in the second round, you replace that marble so you still have a total of 10 marbles and 7 of them will still be red: 7/10
Multiply...
7/10 x 7/10 = 49/100
PROBABILITY: 49/100 (or 49%)
Hoped I helped