First add 7d to both sides:
-22 = 11d
Now divide by 11 both sides
-2 = d
You can work on either side of the equation, I used the right side for the variables because it was easier to add to positive numbers than dealing with negative numbers on the left side:
-7d -4d = 22
-11d =22
d = -2
either way you get the same answer :)
It has 15 things affghhjj ibhcff
Area od pizza, A = Pi*Diameter^2/4
A1 = Pi*8^2/4 = 50.27 in^2
A2 = Pi*10^2/4 = 78.54 in^2
A3 = Pi*12^2/4 = 113.10 in^2
Cost (C) per sq. in;
C1 = 50.27/9 = $5.59
C2 = 78.54/12 = $6.55
C3 = 113.10/18 = $6.28
The best buy is the first pizza with 8 in diameter as it costs the least per sq. inch.