The figure shows an irregular 5-sided figure and a square not drawn to scale. The area of the five-sided figure was thrice the area of the square. After the shaded part was removed, the area of the remaining square became 15% of the total remaining area of both figures. If the area of the shaded part is 80 cm
2, find the remaining area of the 5-sided figure.
|
5-sided figure |
Square |
Difference |
Before |
3x7 = 21 u |
1x7 = 7 u |
2x7 = 14 u |
Change |
- 4 u |
- 4 u |
|
After |
17x1 = 17 u |
3x1 = 3 u |
14x1 = 14 u |
15% =
15100 =
320The difference in the areas remains unchanged. Make the difference in the areas the same. LCM of 2 and 14 is 14.
Area of the shaded part
= 21 u - 17 u
= 4 u
4 u = 80
1 u = 80 ÷ 4 = 20
Remaining area of the 5-sided figure
= 17 u + 3 u
= 20 u
= 20 x 20
= 400 cm
2 Answer(s): 400 cm
2