You will need a total of nearly 53 yards of concrete for your project if my calculations are correct. You'll want to figure a little on the heavy side and perhaps order an additional yard when the truck comes unless you have a metered truck doing the delivery.
Is it 216
That is 216 inches
12X18
To purchase a 12x18 picture frame (in a variety of colors) one can go to a local photo shop. Another option is to purchase online from Sears, Amazon, or Picture Frame.
80
12x18+3=219 I believe
2x108 3x72 4x54 6x36 8x27 9x24 12x18 18x12
216 square feet. Length x width = square feet.
216 square feet. To calculate square feet simply multiply length by width - the result is the area in square feet.
(12-ft x 18-ft) = (4-yd x 6-yd) = 24 square yards
You can use two cake recipes for that size pan.
Any large picture frame that's at least 12x18" will work well, though it depends on the size of one's family.