What are all the methods to finding zeros and factors of higher degree polynomial functions?

Some boys and girls were asked if they had a pet. one third of the group were boys. there were 20 boys. 20% of the girls had a pet. boys with a pet : girls with a pet = 1 : 5 i need to know how many girls there are.

Is this a polynomial function? i need to know asap

The suare root of 9x plus 7 plus the square rot of 2x equall to 7