Mark exercised on a treadmill for 1 hour. He walked first then jogged. He wanted to find out what fraction of the hour he spent walking and what fraction of the hour he spent jogging. He remembers that he set the treadmill at a rate of 3 miles per hour when walking and at a rate of 7 miles per hour when jogging. The treadmill showed that the total distance he walked and jogged was 6 miles. Let x represent the time, in hours, that Mark walked, and let y represent the time, in hours, that he jogged. A system of two equations can be used to represent a model of the situation described. Part A

Which equation is one of the two equations needed to represent the model? Type your answer in the box below.
A.7x+3y=1
B.3x+7y=1
C.7x+3y=6
D.3x+7y=6
Part B

Which equation is the other needed equation to represent the model? Type your answer in the box below.
A. x+y=1
B. x+y=6
C. x+y=60
D.3x+7y=60

Part C

What fraction of an hour did mark spend walking? Write your answer as a decimal. Enter your answer in the box below.

Part D

What fraction of an hour did Mark spend jogging? Write your answer as a decimal. Enter your answer in the box below.