1.
100%-15%=85%
1337:85%=1572,94 lei
100%-10%=90%
1572,94:90%=1747,71 lei
2. nr=x
x/4+x/3+12=x-3
3x+4x+144=12x-36
5x=180
x=36
3. a=suma
a/5+5
a-(a/5+5)=4a/5-5 =rest
(4a/5 -5)*1/5+3=4a/25-1+3=4a/25+2
4a/5-5 -(4a/25+2)=4a/5-5-4a/25-2=(20a-4a)/25-7=16a/25-7 =rest
(16a/25-7)*1/5+2=16a/125-7/5+2=16a/125+3/5
a/5+5+4a/25+2+16a/125+3/5+210=a
a/5+4a/25+16a/125+3/5+217=a
25a+20a+16a+75+27125=125a
64a=27200
a=425 lei
verificare
425 *1/5 =85 lei
425-(85+5)=335 lei
335 *1/5=67 lei
335-(67+3)=265 lei
265 *1/5=53 lei
265-(53+2)=210 lei