Question

the value of a machine depreciates by 10% every year. if it's present value is 35,100,what was its value a year ago

Answer 1

let the value was 100x

depreciation = 10%of 100x. =10x

present value. =35100

100x-10x. =35100

90x.= 35100

x =35100/90

x= 390

so value a year ago was = 100*390= 39,000

Answer 2

35100*100/90 =39000
Depreciates 10% every year..
10%==10/100==1/10=== 10-----9
                                                    9---35100
                                                    1---3900
                                                    10---39000