What is the definition in statistics for sx and sy?

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

Savannah had 40 iris blooms last year this year she had 15% more iris blooms how many more hours blooms did savannah have this year

Ebert used to make $22 an hour, but got a 10% raise. how much more will he make in a 40 hour work week with raise?