Mae'r fformiwla Barnett yn pennu pa gyfran o wariant llywodraeth y DU sy'n mynd i'r Alban, Cymru a Gogledd Iwerddon.

BBC: Cwestiynau Cyllid

For instance, sections of different trains headed from Birmingham, Ala. to Allentown, Pa. would follow each other, getting joined at stops along the way, such as Linwood, N.

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