PV=FV/(1+i)^t
FV=7000, i=3.5%=0.035,t=9
put everything in the formula
PV=7000/(1+0.035)^9
PV=$5136.12
The solution to the system is (90,40)....x = adults and y = child's...so x = 90 (there were 90 adult tickers) and y = 40 (there were 40 child tickets)...u already had the answer right in front of you
You would need to use the distance formula.
Distance = Sqrt((x2-x1)^2+(y2-y1)^2)
Plug in your numbers
Distance = Sqrt((12+4)^2+(12-18)^2)
Distance = 17.09