The cost of petrol rises by 2 cents a liter. last week a man bought 20 liters at the old price. this week he bought 10 liters at the new price. altogether, the petrol costs $9.20. what was the old price for 1 liter?

The old price was $0.30/liter.

Step-by-step explanation:

The original price of petrol was x dollars per liter.

The new price is x + 0.02 dollars per liter.

Last week he bought 20 liters, so he spent 20x.

This week he bought 10 liters, so he spent 10(x + 0.02).

The total he spent in the two weeks is 20x + 10(x + 0.02).

The total he spent is $9.20.

20x + 10(x + 0.02) = 9.20

20x + 10x + 0.2 = 9.2

30x = 9

x = 0.3

The old price was $0.30/liter.

answer

d. 10

explanation

the distance from point y to wx is the height of the triangle.

using pythagoras theorem,

group similar terms to get,

this implies that,

take positive square root of both sides to get,

this implies that,