Answer:
2x + 40 = 600
2x = 560
x = 280.
Your friends guitar costs $280.
Explanation:
Set the equation equal to $600, the cost of the new guitar. Let the variable, x, represent the cost of your friends guitar. Since your guitar was + 40 more than double the cost of your friend’s, this can be written as an equation:
2x + 40 = 600