I need help if yall can help me please​

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)

Solve for x and y: 217x + 131y = 913; 131x + 217y = 827

Given the two similar triangles, how do i find the missing length? if a=4, b=5, and b'=7.5 find a'