1)2m*4n-3a*2b-0.2n*5m+b*5a-5nm+8ab=8mn-6ab-mn+5ab-5mn=2mn+7ab
2)13ab-0.2xy-2a*5b+6x(0.2)y+a(-3)b=13ab-0.2xy-10ab+1.2xy-3ab=0+xy=xy
3)2abc*5a+1цел5/7a^2*7/12bc-(2цел2/3)nk+2/9n^2m(-4цел1/2)k=10a^2bc+12/7a^2*7/12bc-8/3nk+2/9n^2m*(-9/2)k=10a^2bc+a^2bc-8/3kn-n^2mk=11a^2bc-8/3kn-kmn^2
4)3nmk*4n-3/8nm(2цел2/3)nk+2/9n^2m(-4цел1/2)k=3nmk*4n-3/8nm*2цел2/3nk-2/9n^2m*4цел1/2k=(3*4-3/8*2цел2/3-2/9*4цел1/2)kmn*n=(12-3/8*8/3-2/9*9/2)kmn*n=(12-1-1)kmn*n=10kmn^2