Please help im giving 95 points

For what values of the variable x is the expression square root of 7x+14+ square root of 7-x a real number?

Campus rentals rents 2 and 3 bedrooms apartments for $700 ans $900 a month respectively. last month they had six vacant apartments and reported $4600 in lost rent. how many of each type of apartment were vacant?

Xy x xy if a and b are positive integers such that a*b=9 and b*a=72 what is the value of a/b