Упростите выражение:а) 5(х+1,4у)-0,8(2х+у)...

Решите задачу:

$1)5x+7y-1.6x-0.8y=3.4x-6.2y\\ 2)\frac{2}{3}(x-y+z)-(\frac{2x}{3}-y+z)=\frac{2x-2y+2z}{3} - \frac{2x}{3}+y-z=-\frac{2y}{3}+y+\frac{2z}{3}-z = \frac{y}{3}-\frac{z}{3}\\ 3) -a+1.5a+0.1b-a-0.1b=-0.5a\\ 4)-10(\frac{2}{5b}+\frac{1}{2})+\frac{3}{4}(8-b)+5b= -\frac{4}{b} -5+6-\frac{3b}{4}+5b=\frac{-16+4b+17b^2}{4b}$