Suppose 3<a<4 and 4<b<5 Fin all possible values of 1/a+1/b

Question

It should be phrased as

_<1/a + 1/b<_

Answer 1

By the given inequalities we have that 1/4 < 1/a < 1/3 and 1/5 < 1/b < 1/4. Hence, by adding these we get

1/4 + 1/5 < 1/a + 1/b < 1/3 + 1/4.