Whats the answer to 6/7 times 21 with showing ur work

Sadie computes the perimeter of a rectangle by adding the length, l, and width, w, and doubling this sum. eric computes the perimeter of a rectangle by doubling the length, l, doubling the width, w, and adding the doubled amounts. write an equation for sadie’s way of calculating the

Which shows the correct substitution of the values a, b and c from the equation 1=-2x+3x^2+1

Select the conic section that represents the equation. 3x2 + 3y2 -2x + 4 = 0