Total cost is 6.54 for 3 tickets so divide 6.54 by 3 and you get price per ticket which is 2.18. Multiply that by how many tickets you want and you get your final price.
X=number of females 47-x=number of males # of males is 2*(number of females)-7: 47-x= 2x-7 add x to both sides: 47=3x-7 add 7 to both sides: 54=3x divide both sides by 3: x= 18 females 47-18= 29 males