Tìm x

ai 2. Tim x:
a) 75 x x = 1800
4) 76502 - x x = 10512:32
x264 = 1456:52
b) 1855 x = 35
c) x: 204 = 543
x + 532 = 48 x 23
256-(x+61) = 82
9256 532