You multiply straight across, and one number is a fraction and the other is not.
I did the math and I believe the answer is, the y-intercept is 12.3.
For the first question the answer is the second option.
For the second question the answer is the first option.
Hope I didn't mess up for your sake
Marked down 15% means the new price would be 85% of the original price ( 100%-15% - 85%)
Multiply the original price by 85%:
5250 x 0.85 = 4462.50
The new price is $4,462.50