Please please please please please please please please help with my daily thing

What number should be added to the expression x^2+3x+ in order to create a perfect square trinomial? 3/2 3 9/4 9

The dolphins at the webster are fed 1/2 of a bucket of fish each day the sea otters are fed 1/2 as much fish as the dolphins how many buckets of fish are the sea fed each day? simplify you answer and write it as a proper fraction or as a whole or mixed number

Ineed with angles and the measure of them i have abc a is 65 and b is (3x-10) and c is (2x) find the value of x