Question 884312
1. {{{a<b}}} Given, {{{c>0}}} Given
2. {{{ac<bc}}} Multiplication by a positive value ({{{c>0}}}) does not change the inequality (Multiplication rule of inequalities)
3. {{{c<d}}} and {{{b>0}}} Given
4. Same as 2, since {{{d>0}}}
5. From 4, {{{bc<bd}}} and from 2, {{{ac<bc}}} so then,
{{{ac<bc<bd}}}
So 
{{{ac<bd}}}