Devaughn's age is two times Sydney's age. The sum of their ages is 18. What is Sydney's age?

Given the following statements, which is the best

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.

Which shows one way to determine the factors of 4x3 + x2 – 8x – 2 by grouping?