Find the missing numbers:

a)(3^2 × 7^3 × 5^2)^2 × (2^3 × 7^3^)3 = 2^x × 3^y × 5^z × 7^n

b)((2^2 × 7^3)/5^2)^2×((3^2 × 7^3)/5^3)^2 = (2^x × 3^y × 7^z)/5^n

c)[(1/4).(1/3)]^2