Originally Posted by

**coffeegirly99** here goes : (any help appreciated)

a) when driven in town, a car runs at *x* kilometres on each litre of petrol

(i) find in terms of *x* , the number of litres of petrol used when the car is driven 200km in town

number of Liters, V = 200/x

(ii) **when driven in town , the car runs (***x*+4) kilometres on each litre of petrol to go 200km out of town than to go 200km in town. Use this information to write down an equation involving *x* , and show that is simplifies to :

*x^2 + 4x - 160 = 0*

the **bold statement** makes little sense to me ... I understand that in town the car gets x km/L and out of town the car gets (x+4) km/L ... recheck the exact wording.

b) solve the equation *x^2 + 4x - 160 = 0*

$\displaystyle x^2 + 4x = 160$

$\displaystyle x^2 + 4x + 4 = 160 + 4$

$\displaystyle (x + 2)^2 = 164$

$\displaystyle x + 2 = \pm 2\sqrt{41}$

$\displaystyle x = -2 \pm 2\sqrt{41}$

since x represents km, $\displaystyle x = -2 + 2\sqrt{41}$

c)Calculate total volume of petrol used when the car is driven 40km in down and then 120km out of town.

$\displaystyle V = \frac{40}{x} + \frac{120}{x+4}$