(1)x+45=550,
x+45-45=550-45,
x=505;
(2)x-0.52=1.3,
x-0.52+0.52=1.3+0.52,
x=1.82;
(3)x÷3=95,
x÷3×3=95×3,
x=285;
(4)0.9x=2.43,
0.9x÷0.9=2.43÷0.9,
x=2.7.
(1)x+45=550,
x+45-45=550-45,
x=505;
(2)x-0.52=1.3,
x-0.52+0.52=1.3+0.52,
x=1.82;
(3)x÷3=95,
x÷3×3=95×3,
x=285;
(4)0.9x=2.43,
0.9x÷0.9=2.43÷0.9,
x=2.7.