Упростите
1) 12a+6.4a-5-2a-3a+3.6=13.4a-1.4 2) -9+x+2x+6+4x-0.9=7x-3.9 3) 1.6y- 2.4+8-2.5y-1.6y+3.4=-2.5y+10 4)1/6n+5-6+1/3n+1/2n-8=1/6n-1+2/6n+3/6n-8=1n-7