I'm not sure if I'm doing this question right, just need help finding the Left Riemann, Right Riemann and the average of two sims

Find L , RA, and their average for the definite integral below using the indicated value of n. (3 x3 - x) dx , n = 6 N . . .. . The left Riemann sum, L, is 50 (Do not round until the final answer. Then round to three decimal places as needed.) The right Riemann sum, R , is 82 (Do not round until the final answer. Then round to three decimal places as needed.) The average of the two sums is 66 (Type an integer or decimal rounded to three decimal places as needed.)