59. The sum of two angles of a triangle is half of a right angle, and one of these two angles is $5^{\circ}$ less than the other. The degree measure of the smallest angle in the triangle is $\qquad$ $\circ$.

A triangle has two interior angles whose sum is half of a right angle, and one of these angles is $5^{\circ}$ less than the other. The degree measure of the smallest angle in the triangle is $\qquad$ .
Answer: $20^{\circ}$.
Solution: The sum of the two angles is
$$
90 \div 2=45^{\circ} \text {, }
$$

Therefore, the degree measure of the smallest angle in this triangle is
$$
(45-5) \div 2=20^{\circ} \text {. }
$$