Keep on simplifying the radii (Geometry of Circles by HCR)

Two large circles C1 & C2 with radii a=16 & b=25 respectively are touching each other externally & their common tangent line L at the points X1 & X2 respectively. A small circle C3 touches them externally & the tangent line L at the point X3. Again a smaller circle C4 touches circles C3 & C2 externally & the tangent line L at the point X4. Further a smallest circle with a radius r touches circles C3 & C4 externally & the tangent line L at the point X5. The radius r can be written as m⁄n where m & n are co-prime numbers . Find out the value of m+n