xx + x + 5 = 25
x * 11 + x * 1 + 5 = 25
x * (11+1) + 5 = 125
x * 12 = 120
x = 120 : 12
x = 10
(xxx - xx - x) - 25 = 4430
x * 111 -x * 11 - x * 11 - 25 = 4430
x * 99 - 25 = 4430
x * 99 = 4430 + 25
x * 99 = 4455
x = 4455 : 9
x = 45
xxx + xx + x + x = 992
x * 111 + x * 11 + x * 1 + x * 1= 992
x * ( 111 +11 +1+1) = 992
x * 124 = 992
x = 992 : 124
x = 8
xxx + xx + x + x + x + 1 = 1001
=> ( x * 100 + x * 10 + x * 1 ) + ( x * 10 + x * 1 ) + x * 1 + x * 1 + x * 1 = 1001 - 1
=> x * ( 100 + 10 + 1 + 10 + 1 + 1 + 1 + 1 ) = 1000
=> x * 125 = 1000
=> x = 8