(9. Calculati :
a) (16× 12¹⁰ - 4×12¹⁰): 12¹¹
c) 10³×85-10³× 61 - 3 000;
b) 15² - (14: 15+15): 15²
d) 5¹¹– (6×5¹⁰ – 2×5¹⁰)