| ( | 10 | × | 80 100 | + | 10 | × | 60 100 | + | 40 100 | X | ) | × | 6 5 | = | ( | 10 | × | 20 100 | + | 10 | × | 40 100 | + | 60 100 | X | ) |
| Left side of the equation = | 10 | × | 80 100 | × | 6 5 | + | 10 | × | 60 100 | × | 6 5 | + | 40 100 | X | × | 6 5 |
| = | 48 5 | + | 36 5 | + | 12 25 | X |
| = | 84 5 | + | 12 25 | X |
84 5 | + | 12 25 | X | = | ( | 10 | × | 20 100 | + | 10 | × | 40 100 | + | 60 100 | X | ) |
| Right side of the equation = | 10 | × | 20 100 | + | 10 | × | 40 100 | + | 60 100 | X |
| = | 2 | + | 4 | + | 60 100 | X |
| = | 6 | + | 60 100 | X |
84 5 | + | 12 25 | X | = | 6 | + | 60 100 | X |
12 25 | X | − | 60 100 | X | = | 6 | − | 84 5 |
| - | 3 25 | X | = | 6 | − | 84 5 |
| - | 3 25 | X | = | - | 54 5 |
54 5 | = | 3 25 | X |
3 25 | X | = | 54 5 |
| X | = | 54 5 | ÷ | 3 25 |
| = | 54 5 | × | 25 3 |
| = | 18 | × | 5 |
| X | = | 90 |