28.) To find the area that needs to be painted, you need to find the area of each side and add them together. They gave you the triangle faces so you just need to find the area of the rectangles.
Area of a rectangle = Length x Width
Find the area of the bottom rectangle. It's length is 5 and the width is 3:
A = 5 x 3 = 15
Find the are of the other two rectangles. They both have the same length and width. Their lengths are 5 and their widths a are 2.5:
A = 5 x 2.5 = 12.5
Now add all the faces together:
3 + 3 + 15 + 12.5 + 12.5 = 46
ANSWER:
46 meters squared
29.) To find the amount of needed concrete you need to add up the total parts:
2 + 4 + 6 + 1 = 13
This means that the mixture is 4/13 sand. Take the 4/13 and multiply it by 6.5 to get the amount:
(4/13) x 6.5 = 2
ANSWER:
He needs 2 cubic meters of sand.