Question 426356
Son's age x											
Father's age	9x								
5 years later										
Son's age x +5									
Father's age 9x+5							
Father's age 4	times older										
9x+5=4(	x+5)	
9x+5=4x+20			
5x=20-5				
5x=15							
/5									
x=3	Son's age							
x+20=23	years	Father's age