Pls help can someone do this. I'm really struggling here. I'll also give brainlist if you get it right pls don't just answer with something random.

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

Olga bought a new skirt that cost $20. sales tax is 5%. how much did olga pay, including sales tax? 7.

Technicians have installed a center pivot, circular irrigator for a farm that covers 25 acres. a.) how long is the irrigation boom (in feet) from the center pivot to its farthest extent? b.) if the irrigation boom makes 4 full revolutions in a day, how many miles does the end of the boom travel in 5 days?