36/2=18
18 would be your answer the radius is half of the diameter
C.Quadrilateral is the answer for the following because rhombus, trapezoid, isosceles trapezoid have parallel sides.
Try this:
1) note that weight of pure antifreeze before mixing and after mixing is the same. So, if 'x' is weight of pure antifreeze in 50% solution, it is possible to make up equation before mixing: 0.5x+0.2*90.
2) there are 0.2*90=18 gal. of pure antifreeze in the 20% solution. If 'x' gal. is the weight of pure antifreeze in 50% sol. and 18 gal. is the weight of pure antifreeze in 20% sol., it is possible to make up an equation after mixing: 0.4(x+18).
3) using the both parts: 0.5x+0.2*90=0.4(x+18) ⇒ x=54 gal. of <u>pure</u> weight.
4) to find 50% solution of 54 gal. pure weight just 54:0.5=108 gal.
Answer: 108 gal.
This is your perfect answer
<span>The regular octagon has rotational symmetry. Since it is comprised of 8 "equal parts", divide 360º/8 to determine the smallest angle of rotation. 360º/8 = 45º. </span>
