Номер 999

x · 5 = 38 + 52;
x · 5 = 90;
x = 90 : 5;
x = 18;
18 · 5 = 90;
38 + 52 = 90;
90 = 90.

x + 29 = 35 · 4;
x + 29 = 140;
x = 140 – 29;
x = 111;
111 + 29 = 140;
35 · 4 = 140;
140 = 140.

48 : x = 34 – 28;
48 : x = 6;
x = 48 : 6;
x = 8;
48 : 8 = 6;
34 – 28 = 6;
6 = 6.

240 : 3 + x = 260;
80 + x = 260;
x = 260 – 80;
x = 180;
240 : 3 + 180 = 260;
80 + 180 = 260;
260 = 260.

96 : 8 · x = 36;
12 · x = 36;
x = 36 : 12;
x = 3;
96 : 8 · 3 = 36;
12 · 3 = 36;
36 = 36.

x – 200 · 3 = 120;
x – 600 = 120;
x = 120 + 600;
x = 720;
720 – 200 · 3 = 120;
720 – 600 = 120;
120 = 120.