Roots of the equation 3x² -3x-6=0 are -1 and 2,
all choices are given wrong
3*2²-3*2-6=0
12-6-6=0
0=0, which is true , so root is 2
3*20²-3*20-6=0
600-60-6=0
534=0  which is wrong, so root is 2, but not 20 
        
             
        
        
        
The son is 4 years old and the dad is 24 years old.
        
                    
             
        
        
        
116100 will be 90% of the selling price
The will need to sell for 116100 / 90 x 100 = $129000
        
             
        
        
        
8+.90+.07
This the answer because you have to make it as an addition way. 
Hope I helped.
        
                    
             
        
        
        
Isolating the x^2 is the simplest way. it would only be three steps.