РЕШЕНИЕ:
( a + b − _1) : __b__ =
a2−ab___ a ___ b−a
( a + b − _1) : __b__ =
a(a-b)___ a ___ b−a
a + b − (a-b) : __b__ =
a(a-b) __ __ ___ b−a
a + b − a + b : __b__ =
a(a-b) __ __ ___ b−a
2b __ : __b__ =
a(a-b) __ b−a
2b __ ∙ a - b =
a(a-b) __ -b
2 =
- a
2 __ = - 4
- 0.5
Ответ: - 4