1). ( a * 5 ) + 289 = 4004
( a * 5 ) = 4004 - 289
a * 5 = 3715
a = 3715 : 5
a = 743
2). b: ( 1000 - 9 * 65 ) = 8
b : (1000 - 585 ) = 8
b : 415 = 8
b = 8 * 415
b = 3320
3). c + 98 -291 : 3 = 100
c + 98 - 97 = 100
c + 98 = 100 + 97
c +98 = 197
c = 197 - 98
c = 99