( 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