Пусть искомое число равно y. Тогда:
6 - \(\frac{5}{12}\) = \(\frac{7}{4}\) - y
\(\frac{72}{12}\) - \(\frac{5}{12}\) = \(\frac{21}{12}\) - y
\(\frac{67}{12}\) = \(\frac{21}{12}\) - y
y = \(\frac{21}{12}\) - \(\frac{67}{12}\) = -\(\frac{46}{12}\) = -\(\frac{23}{6}\)