a, x × a = aa
x = aa ÷ a
x = 11
b, ab x = abab
x = abab ÷ ab
x = 101
c, abc × x = abcabc
x = abcabc ÷ abc
x = 1001
d, xx + x + 5 = 125
x × (11 + 1) + 5 = 125 - 5
x × 12 = 120
x = 120 ÷12
x = 10
e, xxx + xx + x + x = 992
x × (111 + 11 + 1 + 1) = 992
x × 124 = 992
x = 992 ÷ 124
x = 8
f, 4725 + xxx + xx + x = 54909
x × (111+11+1) = 54909 - 4725
x × 123 = 50184
x = 50184 ÷ 123
x = 408
g, xxx - xx -x - 25 = 4430
x × (111-11-1) = 4430 + 25
x × 99 = 4455
x = 4455 ÷ 99
x = 45
h, xxx + xx + x + x + x + 1 = 1001
x × (111 + 11 + 1 + 1 + 1) = 1001 - 1
x × 125 = 1000
x = 1000 ÷125
x = 8