How much is 31.5 inches width and 23.6 inches length in square inches

Hi my sisters and brothers can tell me the answer because i don’t understand the question

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.

X+ y = 5 ; x - y =3 solve using linear combination