您好，很高兴为您解答：99x45+99x54-99=99x(45+54-1)=99x98=(100-1)x98=9800-98=9702
99x45+99x54-99=99x（45+54-1）=99x98=(100-1)x98=100x98-1x98=9800-98=9702
=99×（45+54-1）=99×98=（100-1）×98=9800-98=9702
