True or false prime numbers are closed under subtraction?

Oscar and julie ashton are celebrating their 15th anniversary by having a reception hall. they have budgeted $4,500 for their reception. if the reception hall charges a $90 cleanup fee plus & 36 per person, find the greatest number of people that they may invite and still stay within their budget.

Paul’s car is 18 feet long. he is making a model of his car that is 1/6 the actual size. what is the length of the model?

The measurement of one angle of a right triangle is 42° what is the measurement of the third angle? (there is no picture)