The answer should be 5 or -5
I can solve with 2 methods:
I. Because the discount is 15 % of 18 $ , the price will be (100-15=85) 85 % of 18 $
18*85/100= 15,3 $ ( the sale price)
II. The discount is 15 % of 18$
15*18/100= 2,7$ ( the discount)
then I decrease it from the regularly price
18$-2,7$=15,3 $ (the sale price)
Personally I believe the first is an easier method.
I hope you understand and you can apply this in every similary problem.
3x+15x = 180
18x = 180
x = 10
10(x+y) + 3x = 180
10x + 10y + 3x = 180
13x + 10y = 180
13(10) + 10y = 180
130 + 10y = 180
10y = 50
y = 5
For the lateral area, don't include the base area. For the surface area, you should include it.
