Question

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

Answer 1

9/20÷[1/2×（2/5+4/5）]
=9/20÷[1/2×2/5+1/2×4/5]
=9/20÷[1/5+2/5]
=9/20÷3/5
=9/20×5/3
3/4