Write 2447457.627 in standard form to a appropriate degree of accuracy

Hello people, i have a math question that i need with, me, i will give the correct one brainiest, and for the other correct people, a and 5 stars.

There are 15 plates and each plate is either 7 or 12 inches diameter. which systems of equations do you use to find the number of 7 inch plates, x and 12 inch plates, y

Which expression can be used to determine the slope of the line that passes through the points -6, three and one, -9