First term from sum and last term

A geometric progression has common ratio $3$ , sum $728$ , and last term $486$ . Find its first term.

~4 minAnswer checked instantlyGeometric progressionSum formula

H. S. Hall & S. R. Knight, Higher Algebra (1891) · Ch. V. Geometrical Progression, Examples V.a, No. 22

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Checked against the answer in H. S. Hall & S. R. Knight, Higher Algebra (1891).