4(7/12) - 7(-5/7)
=28/12 + 35/7
= 14/6 + 35/7
= 49/6 + 35/7
= (497 + 356) / (6*7)
= (343 + 210) / 42
= 553 / 42
= 23/3
= 7 2/3
Поэтому, 4x - 7y при x=7/12 и y=-5/7 равно 7 2/3.
4(7/12) - 7(-5/7)
=28/12 + 35/7
= 14/6 + 35/7
= 49/6 + 35/7
= (497 + 356) / (6*7)
= (343 + 210) / 42
= 553 / 42
= 23/3
= 7 2/3
Поэтому, 4x - 7y при x=7/12 и y=-5/7 равно 7 2/3.