The portion of a student’s ballpoint pen that contains the ink is a cylinder with a diameter of 0.400 cm and a height of 11.5 cm. if the ink lasts 7 weeks, what is the volume of ink that the student uses each week?

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

In the figure below, ∠dec ≅ ∠dce, ∠b ≅ ∠f, and segment df is congruent to segment bd. point c is the point of intersection between segment ag and segment bd, while point e is the point of intersection between segment ag and segment df. the figure shows a polygon comprised of three triangles, abc, dec, and gfe. prove δabc ≅ δgfe.

Mat bought a phone for $100. he has to pay $30 per mouth. if he has paid $640 in total, how many mouth has he had the phone?