Can someone please show me how to solve 7 and 8

7. At a 4% discount rate, determine the present value for the following time profile of costs Time Period Costs 0 S10 $8 $6 $5 $10 Spri 8. At a 5% discount rate, determine the net present value for the following time profile of costs Time Period Benefits Costs Net Benefits S5 $80 $30 $40 40 $20 $60 $10 $90 $10