Volume of 1 ball = 4/3 π r³ = 4/3 (3.14) (2.25 ÷ 2)³ = 5.961 in³
Volume of 3 balls = 5.961 x 3 = 17.883 in³
Volume of cylinder = πr²h = (3.14) (2.25 ÷ 2)² (6.75) = 26.825 in³
Empty Space = 26.825 - 17.883 = 8.94 in³ (nearest hundredth)
Answer: 8.94 in³
This is an ellipse.
Equation of an ellipse: 
Let's find the center point first. We can do this by finding out the midpoint between the vertices or the foci.
(-9+7)/2=-1
Center: (-1,3)
Now we need to find a and b (length along x and length along y).
We know "a". It is the distance between the center and the right or left bound.
a=7-(-1)=8
To find out "b", first see that...
b^2=a^2-(distance from center to foci)^2
foci distance=3-(-1)=4
b^2=8^2-4^2
b^2=64-16
b^2=48
b=4√3
answer: 
2x + 3x + 5x = 180
10x = 180
x = 18
2x = 36, 3x = 54, 5x = 90
They add up to 180 (definition of sum of angles of a triangle.)
If he made 25 percent profit, the selling price (1200 naira) is 125 percent.
If 125% is equal to 1200 naira
100 percent (the original) will be 100 × 1200 divided by 125
Which is 120000 ÷ 125
Therefore, the cost price is 960 naira