The cost of 4L of oil and 50 L of gastoline is $42.50. The cost of 3L of oil and 35 L of gasoline is $30.30. Find the cost of 1 L of oil and 1 L of gasoline

Question

Solve algebraically using system of equations 

Answer 1

Hi Emma,

 

Let the cost of one liter of oil be x and one liter of gasoline be y.

 

4x + 50y = 42.5

3x + 35y = 30.3

 

I will eliminate x. Multiply the first equation by 3 and the second one by -4.

 

3*(4x + 50y = 42.5) 
-4*(3x + 35y = 30.3)

 

12x + 150y = 127.5

-12x - 140y = -121.2

+--------------------------

0 + 10 y = 6.3

y = 0.63

Cost of one liter of gasoline is $0.63 or 63 cents.

4x + 50y = 42.5

4x + 50*0.63 = 42.5

4x = 11

x = 2.75

Cost of one liter of oil is $2.75