a)30a²b/5*2b-(3a+a*2ab)=(30/10)*(b/b)*a²-a(3+2ab)=3a²-3a-2a²b
b)x²y-(3x*yx+2y²x)+15x²y²/3x=x²y-3x²y-2xy²+15x²y²=-2x²y-2xy²+15x²y²
c)12m²n⁵/4mn⁵+21mn/6m⁴n²*2m⁵n-½m=(12/4)*(m²⁻¹)*(n⁵⁻⁵)+
+(21/12)*(m¹-⁹)(n¹⁻³)-1/2m=3m-1/2m+(7/4)*m⁻⁸*n⁻²=2½m+
+(7/4)*m⁻⁸*n⁻²
d)3u³v-3vu*5u²+(3u²v*2u-vu³)/4uv= 3u³v-15u³v+6u³v-u³v=-7u³v
