21. In this assignment, the conclusion of the Internal Rate of Return (IRR) method as to the best paver coincides with the conclusion of the Net Present Worth (NPW) method. 22. A99's External Rate of Return (ERR). 23. C77's External Rate of Return (ERR). 24. The incremental External Rate of Return (AERR) between pavers B88 and A99. 25. The incremental External Rate of Return (AERR) between pavers C77 and A99