Answer:
Brian have £105 left.
Step-by-step explanation:
Given,
Amount earned by Brian per week = £168
Fraction spent on rent = 1/8
Amount spent on rent = 1/8 x 168
Amount spent on rent = £42
Fraction spent on food = 1/8
Amount spent on food = 1/8 x 168
Amount spent on food = £21
Amount left = Amount earned - amount spent on rent - amount spent on food
Amount left = 168 - 42 - 21
Amount left = £105
Brian have £105 left.
I hope this helps you
Answer:
the rate of change of the water depth when the water depth is 10 ft is; 
Step-by-step explanation:
Given that:
the inverted conical water tank with a height of 20 ft and a radius of 8 ft is drained through a hole in the vertex (bottom) at a rate of 4 ft^3/sec.
We are meant to find the rate of change of the water depth when the water depth is 10 ft.
The diagrammatic expression below clearly interprets the question.
From the image below, assuming h = the depth of the tank at a time t and r = radius of the cone shaped at a time t
Then the similar triangles ΔOCD and ΔOAB is as follows:
( similar triangle property)


h = 2.5r

The volume of the water in the tank is represented by the equation:



The rate of change of the water depth is :

Since the water is drained through a hole in the vertex (bottom) at a rate of 4 ft^3/sec
Then,

Therefore,

the rate of change of the water at depth h = 10 ft is:




Thus, the rate of change of the water depth when the water depth is 10 ft is; 
X=-2
5-4=1
so whatever is square rooted must be equal to 1
1 squared is 1
-2+3 is one