Help please! I’m so confused about the first question. What does Q mean? Like represent?

What number must you add to complete the square x^2+12x=16

If the measure of xyz is 81 what is the measure of yz

Trish receives $450 on the first of each month. josh receives $450 on the last day of each month. both trish and josh will receive payments for next four years. at a discount rate of 9.5 percent, what is the difference in the present value of these two sets of payments?