Arthur. has two different plans for a dog walking business. he would charge his customers weekly for either plan.
plan a: he charges the customers $ 12 per dog walk $12 for grooming at the end of the week
plan b: he charges the customers $ 20 per dog walk and then offers free grooming at the end of the walk.

solution:

the given function is ,

      =

the three roots of this quadratic function is , 0 ,8 and 10.all the roots are real and rational.

if a quadratic equation is of the form ,

sum of the roots = a + b +c= 0+8+10=18=  

product of roots taken two at a time = a b + b c+ c a = 0+80+0=80 =  

product of roots = a b c = 0=  

there are 11 doors in a hall starting from 0 to 11.the entry in the hall is permitted through gate number 0 and exit is allowed through only gate number 8 and 10.so, three roots(0,8,10) of quadratic function is given by entry and exit route of this hall.

its 60

4 x 12 = 48

3 x 4 = 12

48 + 12 = 60

yeeeet

a+b=c is your answer