First we will find the interest on:
P = $235 principal
t = 2 years
r = 0.1415 annual rate
A = future value
I = A - P the interest
A = P(1 + r)^t
A = 235(1 + 0.1415)^2
A = $306.21
I = A - P
I = $306.21 - $235
I = $71.21
the interest was $71.21.
Next lets find the lifetime cost value:
Lifetime cost value = 306.21 + 5*1.56*52 + 5*0.78*52 = $914.61 (considering that 1 year = 52 weeks)
Now lets find the percentage what percentage the interest is of the lifetime cost:
(71.21/914.61)*100 = 7.79%
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Its 23.1 one because in 23 minutes they travel three miles
The cost is £79.76. Since the car covers 560 miles and 34.5 miles is travelled by one gallon. So, dividing 560 by 34.5 we get 16.23. Since 1 gallon is 4.55 litres, 16.23 gallons is 73.8465. Now the cost of petrol is £1.08 per litre. So, multiplying 73.8465 by £1.08 we have £79.76


so the ODE is indeed exact and there is a solution of the form
. We have




With
, we have

so
