Answer:
radius 12 units = 452.16 units²
diameter 16.8 units = 221.5584 units²
radius 3.4 units = 36.2984 units²
diameter 10 units = 78.5 units²
Formula for area of circle: 
P= $48c + $17.76 hope this helps
uhm 1+1 is 2 or 213456534578342758790893247234030825793406867452089 im not sure
x+y=5
-x -x
Equals:
y=-x+5
Now you have:
y=-x+5
x-y=1
Insert -x+5 into y
x-x+5=1
Combine like terms
2x+5=1
Subtract 5.
2x=-4
Divide 2.
Answer: x=-2