a)
\dots= 2x-0,2-3x-0,5=-x-0,7
b)
(6a^2+2a+1)-(-3a^2-2a+5)=6a^2+2a+1+3a^2+2a-5=9a^2+4a-4
c)
(12i 1/2m^2+3i 3/4n^2+2,4)=12,5m^2+3,75n^2+2,4
d)
(1,5x^2y-3/4x^2-15)-(2/5x^2y-2i 2/3-1/8x^2=
1,5x^2y-0,75x^2-15-0,4x^2y-7\frac{1}{3}-0,125x^2=1,1x^2y-0,875x^2-22\frac{1}{3}