| 1 | ÷ | 3 | × | s | + | 1 | ÷ | 2 | = | 9 | ÷ | 4 | + | 1 | ÷ | 4 | × | s |
| Left side of the equation = | 1 3 | s | + | 1 2 |
1 3 | s | + | 1 2 | = | 9 | ÷ | 4 | + | 1 | ÷ | 4 | × | s |
| Right side of the equation = | 9 4 | + | 1 4 | s |
1 3 | s | + | 1 2 | = | 9 4 | + | 1 4 | s |
1 3 | s | − | 1 4 | s | = | 9 4 | − | 1 2 |
1 12 | s | = | 9 4 | − | 1 2 |
1 12 | s | = | 7 4 |
| s | = | 7 4 | ÷ | 1 12 |
| = | 7 4 | × | 12 |
| = | 7 | × | 3 |
| s | = | 21 |