Sucrose hydrolysis gives an equimolar mixture of D-glucose (specific rotation $+52.6^{\circ }$) and D-fructose (specific rotation $-92.4^{\circ }$). The two have the same molar mass, so the mixture rotation is the simple mean of the two. Give the specific rotation of the mixture in degrees, to one decimal place (include the sign).

Numerical answer type, tolerance 0.1.