2,4(3x+5y)-4y при 0,9x+y=2

Question

2,4(3x+5y)-4y при 0,9x+y=2

Answer 1

Y=2-0.9x
2.4(3x+5y)-4y
2.4(3x+5*(2-0.9x))-4*(2-0.9x)=
=2.4(3x+10-4.5x)-8+3.6x=
=2.4(10-1.5x)-8+3.6x=
=24-3.6x-8+3.6x=
=16-3.6x+3.6x=
=16
Ответ 16