Will a geometric figure and its rotated image always, sometimes or never have the same perimeter

Lisa berry plans to rent an apartment for $1,090 per month. she estimates the annual expense will be as shown on the chart below. what is her average monthly cost?

If t17 = 3 (t5) in an arithmetic progression, find t1 in terms of d.

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