Hello from MrBillDoesMath!
Answer:
See Discussion below
Discussion:
51^7 - 51^6 = => as 51^7 = 51^6 * 51
51^6*51 - 51^6 = => factor 51^6 form each terms
51^6(51 - 1) = => as 51 -1 - 50
51^6* 50 = => as 50 - 2 * 25
51^6 ( 25*2)
so the original expression is divisible by 25
Thank you,
MrB
