( 1):X-60%X= 160
Solution: X-0.6X= 160
0.4X= 160
X= 160÷0.4
X= 400
(2):50%X+ 1 10%X=4
Solution: 0.5X+ 1. 1X=4.
1.6X=4
X=4÷ 1.6
X=2.5
2. Non-type calculation
( 1)、 1÷( 1-75%)
= 1÷( 1-0.75)
= 1÷0.25
=4
(2)、200×( 1-20%)
=200×( 1-0.2)
=200×0.8
= 160