1) 0,5a'c'(a' - (2 + 6) - 0,5ac- 0,5ad; 2) 4,8x8y? – (12xøy - 6) - 2,4x"y" (2xy - 5y + 3); 3) 2,5t8s1°(4t– 6c2 - 3) + 15tc"910 - 10t0g10; 4) 9a20516 – 1,8a10818 – 0,9a56°(10a1567 + 2a5bº). -​