Gūlǎolao bāshí duō suì le, shēntǐ hái hěn yìnglǎng.
My great-aunt is over eighty but still very robust.
Tips
culture
Chinese kinship is exact: 姑姥姥 = the sister of your maternal grandfather (姥爷). Compare 姨姥姥 (maternal grandmother's sister), 姑奶奶 (paternal grandfather's sister), and 姨奶奶 (paternal grandmother's sister). English just calls them all 'great-aunt.'