| ( | X | + | 1 2 | ) | × | 6 5 | × | 7 100 | = | 63 100 |
| Left side of the equation = | ( | X | + | 1 2 | ) | × | 21 250 |
| ( | X | + | 1 2 | ) | × | 21 250 | = | 63 100 |
| Left side of the equation = | X | × | 21 250 | + | 1 2 | × | 21 250 |
| = | X | × | 21 250 | + | 21 500 |
21 250 | X | + | 21 500 | = | 63 100 |
21 250 | X | = | 63 100 | − | 21 500 |
21 250 | X | = | 147 250 |
| X | = | 147 250 | ÷ | 21 250 |
| = | 147 250 | × | 250 21 |
| = | 7 | × | 1 |
| X | = | 7 |