二十分之九除以【二分之一乘(五分之二加五分之四)】简便计算

9/20÷[1/2×（2/5+4/5）]

=9/20÷[1/2×2/5+1/2×4/5]

=9/败激20÷[1/5+2/5]

=9/20÷3/察弯袜5

=9/20×5/闹歼3

3/4