To solve this question, let's find the surface area of the entire pie and then divide it by 6 for each slice.
The area of a circle is pi*r^2. We are given the diameter, so divide that by 2 to get the radius.
Now that you have the area, divide by 6. That is the area of each slice. The problem asks for the area of 2 slices though, so multiply that by 2.
Let the cost of soap be x,
cost of razors = x + 2.5
total cost = 2x + 2.5
2x + 2.5 = 5.5
2x = 3
x = 1.5
cost of razors = 1.5 + 2.5
= 4
The cost of the packet of razors and bar of soap is £4.00 and £1.50 respectively.
Dependant because one event cannot happen without the other taking place
So, these are actually pretty simple once you learn the equality used to solve for "x" and when to implement this method. You can use this equality to solve for a segment "x" anytime that two secant lines cutting through a circle come from the same point outside the circle.
Secant: by geometric definition is just a straight line that cuts a curve into multiple pieces.
I did one of them for you hopefully you can use my work for "a" to help you solve for "b".
For a. I got x=7.