| ( | R | + | 10 | ) | ( | 5 | + | 1 2 | R | ) | = | 25 | R |
| Left side of the equation = | R | ( | 5 | + | 1 2 | R | ) | + | 10 | ( | 5 | + | 1 2 | R | ) |
| = | R | × | 5 | + | R | × | 1 2 | R | + | 10 | ( | 5 | + | 1 2 | R | ) |
| = | 5 | R | + | R | × | 1 2 | R | + | 10 | × | 5 | + | 10 | × | 1 2 | R |
| = | 5 | R | + | R | × | 1 2 | R | + | 50 | + | 5 | R |
| = | 10 | R | + | R | × | 1 2 | R | + | 50 |
| 10 | R | + | R | × | 1 2 | R | + | 50 | = | 25 | R |