What is the value of x, if 105% of 90 is equal to 200% of x?

Bring the fraction a/a-4 to a denominator of 16-a^2

Right triangle xyz has a right angle at vertex y and a hypotenuse that measures 24 cm. angle zxy measures 70º. what is the length of line segment xy? round to the nearest tenth. 8.2 cm 8.7 cm 22.6 m 25.5 cm

How is this equation completed? i cannot find any examples in the book.