Right fractions equal to 2/3 and 2/5 that have denominations of 15

How to choose the sign of the radical in the denominator of the formula for the distance from a point to a line.

Clarence wants to buy a new car. he finds an ad for a car that costs 27,200 dollars. suppose his local sales tax is 7%. -how much would he have to pay? -what is the cost of the car including tax? -if clarence has 29,864 saved, can he pay cash to buy the car?

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