1,2<x<1,3 17<y<18 Оценить:a)x+y,б)x-y,в)-y,г)xy,д)1/y

Решите задачу:

$1,2\ \textless \ x\ \textless \ 1,3\\\\17\ \textless \ y\ \textless \ 18\\\\18,2\ \textless \ x+y\ \textless \ 19,3\\\\-18\ \textless \ -y\ \textless \ -17\\\\-16,8\ \textless \ x-y\ \textless \ -15,7\\\\20,4\ \textless \ xy\ \textless \ 23,4\\\\\frac{1}{18}\ \textless \ \frac{1}{y} \ \textless \ \frac{1}{17}$