Help me with this is pls I’ll give if correct

How do you solving the solution of each system using elimination?

What is the simplified form of (3.25x10^3)(7.8x10^6) written in scientific notation?

Prove the divisibility of the following numbers: 25^9 + 5^7 is divisible by 30.also, read as (25 to the power of 9) + (5 to the power of 7) is divisible by 30. blank x 30what is the blank? ( it should be expressed in exponent form)