Step-by-step explanation:
Let the no. of guests be x.
x = (660-160)/20
=> x = 500/20
=> x = 25
ANSWER: He can invite 25 guests.
ALTERNATIVE METHOD:
Money needed to rent the space= $160
His budget= $660
So, money left= $(660-160) = $500
Money needed per guest= $20
Guests he can invite with his budget= 500/20 = 25
So, He can invite 25 guests.
Hope it helps u!