45 - ( x + 45 - 3 ) = l -7 + 3 l
45 - x - 45 + 3 = 4
45 - x - 45 = 4 - 3
45 - x - 45 = 1
45 - x = 1 + 45
45 - x = 46
=> x = 45 - 46
=> x = -1
Vậy x = -1
\(45-x-45+3=|-4|^{ }_{ }_{ }\)\(|^{ }_{ }\)
\(3-x=4\)
\(x=-1\)
45 - x - 45 + 3 = |-7+3| => -x + 3 = |-4| => -x + 3 = 4 => -x = 1 => x = -1