Simplify : 8^3a × 2^5 × 2^2a/4 × 2^11a × 2^-2a

Simplifying the expression : Hence, .

If 2160 = 2^a.3^b.5^c, find a, b and c. Hence, calculate the value of 3^a × 2^-b × 5^-c.

If 1960 = 2^a.5^b.7^c, calculate the value of 2^-a.7^b.5^-c.