Your input: 3/4-2/5*7/12

Intepretation: \(\frac{3}{4}-\frac{2}{5}\cdot \frac{7}{12}\)

Expand the fractions:

\(=\frac{3}{4}-\frac{14}{60}\)

Reduce the fractions' denominator:

\(=\frac{45}{60}-\frac{14}{60}\)

Subtract:

\(=\frac{31}{60}\)

\(=0.516666...\)

Q.E.D.