3n - 2n- 6h + 9

Pls help ASAP

Carson has only $20 bills and $10 bill in her wallet. the total value of the bills is $50. she has 1 more $20 bill than $10 bills. how many each kind of bill does carson have? a. one $20 and two $10 bills b. two $20 bills and one $10 bill c. one $20 bills and three $10 bills d. two $20 bills and two $10 bills

How do i do this? i don’t understand

Enter the missing numbers in the boxes to complete the table of equivalent ratios.time (min) distance (km)? 36 9? 1512 ?