If 25% of a number is 15, find 5% of that number?

What is the measure of x, in degrees

The radius of the circle is 4 cm and the measure of the central angle is 90° the area of the sector with a central angle measuring 90° and radius of length 4 cm is vt cm the triangle in the sector is 4 cm the area of the triangle is v/cm² the area of the segment of the circle is (471 - ) cm?

Can someone me out here and the tell me the greatest common factor