A metal rod A of 25 cm length expands by 0.050 cm when its temprature is raised frmo `0^@C` to `100^@C`. Another rod B of a different metal of length 40 cm expands by 0.040 cm for the same rise in temperature. A third rod C of 50 cm length is made up of pieces of rods A and B placed end to end expands by 0.03 cm on heating from `0^@C` to `50^@C`. Find the lengths of each portion of the composite rod C.