Question

脱式计算． 248×3-378= （434-399）÷7= 762+138-542=

Answer 1

（1）248×3-378
=744-378
=366；
（2）（434-399）÷7
=35÷7
=5；
（3）762+138-542
=762-542+138
=220+138
=358．