may someone help me with this?? QUESTION: Write the phrase as an expression 5 times a number d An expression is. i put already d-15 but it was wrong so yes i need help

1) prove that 731^3−631^3 is divisible by 100 2) prove that 99^3−74^3 is divisible by 25

(60 points) explain this in detail

Solve: 25 points find the fifth term of an increasing geometric progression if the first term is equal to 7−3 √5 and each term (starting with the second) is equal to the difference of the term following it and the term preceding it.