Pls help extra points

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

Asmall business produces and sells balls. the fixed costs are $20 and each ball costs $4.32 to produce. each ball sells for $8.32. write the equations for the total cost, c, and the revenue, r, then use the graphing method to determine how many balls must be sold to break even.

Janice determined there were 10 possible outcomes when tossing two coins and spinning a spinner numbered 1 through 6. what is the correct number? what might have been janice's error?