Explanation:
Thursday = x
Friday = 2x (Since thursday is x and she landed up selling twice the amount she did on thursday, friday would be 2x)
Thursday + Friday = 108
For this problem you would need to find the value of x so you would need to substitute x into the equation that was created for the oranges sold on both the days
Thursday + Friday = x+2x = 108
x +2x = 108
3x = 108
x = 108/3
x= 36
Since x is thursday, Marta sold 36 oranges on thursday
To find the amount of oranges sold on friday you would need to multiply x, which is 36, by 2
2x = 2(36) = 72
72 oranges were sold on friday
Hope this helps!!!