Lets say x regular tickets were sold

y student And z member tickets

So

x+y+z= 750......(1-total tickets)

y=x+20...........(2-its given)

Put 2 in 1'

2x+z= 730.............(3)

For total earning

10x+5y+7z= 5400

10x + 5(x+ 20) +7z =5400

16x + 7z = 5300...............(4)

solve using 3 and 4

16x + 7(730-2x) = 5300

2x + 5110 =5300

x = 190/2 = 85 _______________EDIT: 95

y= 85 +20 = 105____________EDIT : 95+20 = 115

z =730-(2*85) = 790-170= 620_______EDIT:730-190= 540