x- pret initial
x-10x/100=A - pretul dupa prima reducere
A-10A/100=243
A-10A/100=243
A-A/10=243
10A-A=2430
9A=2430
A=270
x-10x/100=270
x-x/10=270
10x-x=2700
9x=2700
x=300 - pret initial
300-300b/100=243
30 000-300b=24300
5700=300b
b=5700/300
b=19
Deci s-a micsorat cu 19 %