REGULA DE 3 SIMPLA
120 lei----------------100%
126----------------------x
______________________
120/126=100%/x% => x=126*100/120=105%
105%-100%=5%
b)5400-------------------100%
4860--------------------------x
_________________________
5400/4860=100%/x
x=4860*100/5400=90%
100%-90%=10%
se ieftineste cu 10 %
c) \
p=pretul initial
scumpirea=15p/100
pretul final= p+15p/100=460 lei
115p/100=460=>
p=460*100/115=400lei