7980000 | = | 100 | ( | 20000 | - | 600 | m | ) | + | 80 | ( | 30000 | - | 400 | m | ) | + | ( | 160 | - | m | ) | ( | 20000 | + | 1000 | m | ) |
Right side of the equation = | 100 | × | 20000 | - | 100 | × | 600 | m | + | 80 | ( | 30000 | - | 400 | m | ) | + | ( | 160 | - | m | ) | ( | 20000 | + | 1000 | m | ) |
= | 2000000 | - | 60000 | m | + | 80 | ( | 30000 | - | 400 | m | ) | + | ( | 160 | - | m | ) | ( | 20000 | + | 1000 | m | ) |
= | 2000000 | - | 60000 | m | + | 80 | × | 30000 | - | 80 | × | 400 | m | + | ( | 160 | - | m | ) | ( | 20000 | + | 1000 | m | ) |
= | 2000000 | - | 60000 | m | + | 2400000 | - | 32000 | m | + | ( | 160 | - | m | ) | ( | 20000 | + | 1000 | m | ) |
= | 4400000 | - | 92000 | m | + | ( | 160 | - | m | ) | ( | 20000 | + | 1000 | m | ) |
= | 4400000 | - | 92000 | m | + | 160 | ( | 20000 | + | 1000 | m | ) | - | m | ( | 20000 | + | 1000 | m | ) |
= | 4400000 | - | 92000 | m | + | 160 | × | 20000 | + | 160 | × | 1000 | m | - | m | ( | 20000 | + | 1000 | m | ) |
= | 4400000 | - | 92000 | m | + | 3200000 | + | 160000 | m | - | m | ( | 20000 | + | 1000 | m | ) |
= | 7600000 | + | 68000 | m | - | m | ( | 20000 | + | 1000 | m | ) |
= | 7600000 | + | 68000 | m | - | m | × | 20000 | - | m | × | 1000 | m |
= | 7600000 | + | 48000 | m | - | m | × | 1000 | m |
7980000 | = | 7600000 | + | 48000 | m | - | m | × | 1000 | m |