A square has four even sides and the perimeter is equal to the sum of all of the sides.

So we can evaluate the equation for P and then solve for s.
Answer: (3)12 + 6x = 84
Step-by-step explanation:
We know he definitely bought 3 books for $12 each so we immediately put that in the equation. Then we add that to the unknown (6 books times however much he bought them for) and then we equal it to 84 (his budget). Now we do 3 x 12 which is 36. Our new equation is 36 + 6x = 84. 84 - 36 = 48 so we know 6x = 48. Now divide 48 by 6 to get rid of the 6 and we learn that the variable equals 8. So, x = 8. We now know that he bought 6 books at 8 dollars each.
150
explain:
100/28*42=x which turns into x=150
He spent 560. Just multiply 70 with 8
Answer:
9pi
Step-by-step explanation:
circumference= 2 (pi) (r)
radius = diameter \ 2
r = 9 \ 2 = 4.5in.
c = 2 (pi) (4.5)
c = 9pi or 28.3in.
Hope this helps!