a) $$485979 + 691 \cdot 308 = 485979 + 213828 = 699807$$
б) $$409 \cdot 539 - 179888 = 220451 - 179888 = 40563$$
в) $$15^3 - 3^3 \cdot 5 = 3375 - 27 \cdot 5 = 3375 - 135 = 3240$$
г) $$(10^3 - 6^3) : (2^4 \cdot 7^2) = (1000 - 216) : (16 \cdot 49) = 784 : 784 = 1$$