Investors buy a studio apartment for $200,000 of this amount they have a down payment of $40,000 Their down payment is what percent of the purchase price? what percent of the purchase price would a $90,000 down payment be?

How to do this , and can some one explain

It says factor each expression 49x-28?

The distribution of the amount of money spent by students for textbooks in a semester is approximately normal in shape with a mean of $235 and a standard deviation of $20. according to the standard deviation rule, how much did almost all (99.7%) of the students spend on textbooks in a semester?