16. a+15/100*a=31,625
a+3/20*a=31.625
a(20/20+3/20)=31.625
a*23/20=31.625
a=31.625*20/23
a=27.5 lei costa produsul inainte de a doua scumpire
a+10/100*a=27.5
a(1/10+10/10)=27.5
a*11/10=27.5
a=27.5*10/11=25 lei
initial produsul a costat 25 lei.
o alta modalitate mai simpla:
31.625/1.15=27.5
27.5/1.10=25
17. 99.36*1.08=107.31
107.31*1.10=118.04 lei a costat la inceput bicicleta
