What does interpret mean in algebra

Which expression is equivalent to? assume x > 0 and y > 0.

The center of the circumscribed circle lies on line segment and the longest side of the triangle is equal to the of the circle.

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.