( | 31 | − | 25 | ) | x | + | ( | 36 | − | 28 | ) | ( | 100 | − | x | ) | = | 720 |
Left side of the equation = | 31 | x | − | 25 | x | + | ( | 36 | − | 28 | ) | ( | 100 | − | x | ) |
= | 6 | x | + | ( | 36 | − | 28 | ) | ( | 100 | − | x | ) |
= | 6 | x | + | 36 | ( | 100 | − | x | ) | − | 28 | ( | 100 | − | x | ) |
= | 6 | x | + | 36 | × | 100 | − | 36 | x | − | 28 | ( | 100 | − | x | ) |
= | 6 | x | + | 3600 | − | 36 | x | − | 28 | ( | 100 | − | x | ) |
= | - | 30 | x | + | 3600 | − | 28 | ( | 100 | − | x | ) |
= | - | 30 | x | + | 3600 | − | 28 | × | 100 | + | 28 | x |
= | - | 30 | x | + | 3600 | − | 2800 | + | 28 | x |
= | - | 2 | x | + | 800 |
- | 2 | x | + | 800 | = | 720 |
- | 2 | x | = | 720 | − | 800 |
- | 2 | x | = | - | 80 |
80 | = | 2 | x |
2 | x | = | 80 |
x | = | 80 | ÷ | 2 |
= | 80 | × | 1 2 |
= | 40 | × | 1 |
x | = | 40 |