(1) 5/8× 5/6 + 1/6 × 5/8
=5/8×(1/6 + 5/6)
=5/8 × 1
=5/8
(2) 9/17 × 7/81 × 17
=9/17 × 17 × 7/81
=9× 7/81
=7/9
希望我的回答对你有所帮助.