Answer:
Each apple costs $1.20 and each orange costs $1.
Explanation:
Let x represent the number of apples and y represent the number of oranges.
For the fruit you bought, 5 apples and 4 oranges, we have 5x+4y. This costs $10. This gives us the equation
5x+4y = 10
For the fruit your friend bought, 5 apples and 5 oranges, we have 5x+5y. This costs $11. This gives us the equation
5x+5y = 11
Together we have the system

We will eliminate x by subtracting the bottom equation from the top:

Divide both sides by -1:
-1y/-1 = -1/-1
y = 1
Each orange costs $1.
Substitute this into the first equation:
5x+4(1) = 10
5x+4 = 10
Subtract 4 from each side:
5x+4-4 = 10-4
5x = 6
Divide both sides by 5:
5x/5 = 6/5
x = 1.2
Each apple costs $1.20.