###Human: At Mario's barbershop haircuts are 50% more expensive during the weekends. If Mario paid $18 for his last haircut on Monday, how much he would have paid the day before?, ### Assistant: Mario's $18 cut on Monday would have been 50% more expensive on Sunday or $18*50% = $9 more expensive
That means he would have paid $9 more on Sunday than what he paid ($18) on Monday or $9+$18 = $27 
 So the answer is :  27