a, \(\dfrac{254\times399-145}{254+399\times253}\)
= \(\dfrac{\left(253+1\right)\times399-`45}{254+399\times253}\)
= \(\dfrac{253\times399+399-145}{253\times399+254}\)
= \(\dfrac{253\times399+254}{253\times399+254}\)
= 1
b, \(\dfrac{5932+6001\times5931}{5932\times6001-69}\)
= \(\dfrac{5932+6001\times5931}{\left(5931+1\right)\times6001-69}\)
= \(\dfrac{5932+6001\times5931}{5931\times6001+6001-69}\)
= \(\dfrac{5932+6001\times5931}{5931\times6001+5932}\)
= 1