400 : 1kg
400 : 1000
1 : 2.5
n = 2.5
check the picture below.
so the playground is really just 3 rectangles and one triangle, now the triangle has a base of 8 and a height of 6. We can simply get the area of each figure, sum them up and that's the area of the playground.

The answer is d because 4+8=12 and they are 4 units away from eachother:)
If the temperature of the egg is x, then if x is below 23 (x<23), they rarely hatch. If x is greater than 33 (x>33), they also rarely hatch. For them to not rarely hatch, then x must be not below 23 (greater than or equal to) and not above 33 (less than or equal to), resulting in our compound equality being
23≤x≤33 and our pair of simple inequalities being x≥23 and x≤33.