а) 81-0,75 + ($$\frac{1}{125}$$)$$^{-\frac{1}{3}}$$ - ($$\frac{1}{32}$$)$$^{-\frac{3}{5}}$$ = (34)-3/4 + (125)1/3 - (32)3/5 = 3-3 + 5 - (25)3/5 = $$\frac{1}{27}$$ + 5 - 23 = $$\frac{1}{27}$$ + 5 - 8 = $$\frac{1}{27}$$ - 3 = $$\frac{1}{27}$$ - $$\frac{81}{27}$$ = -$$\frac{80}{27}$$ = -2$$\frac{26}{27}
б) 0,001-1/3 - (-2)-2 ⋅ 642/3 - 8-1/3 + (90)$$^2$$ = (1/1000)-1/3 - 1/4 ⋅ (26)2/3 - (23)-1/3 + 1 = 10001/3 - 1/4 ⋅ 24 - 2-1 + 1 = 10 - 1/4 ⋅ 16 - 1/2 + 1 = 10 - 4 - 1/2 + 1 = 7 - 1/2 = 6$$\frac{1}{2}
Ответ: а) -2$$\frac{26}{27}$$; б) 6$$\frac{1}{2}$$