1) a/2=b/5=c/11
a=2b/5
c=11b/5
a+b+c=90
2b/5+b+11b/5=90
2b+5b+11b=90x5
18b=450
b=450:18
b=25
a=2x25:5=50:5=10
c=11x25:5=11x5=55
10+25+55=90
2)
luni=30a/100
marti=40/100(a-30a/100)=40/100x70a/100=28a/100=7a/25
miercuri=84 lei
a=30a/100+7a/25+84
100a=30a+28a+8400
100a-58a=8400
42a=8400
a=8400:42
a=200 lei a avut Andrei inainte de a o cheltui
marti=7a/25=7x200/25=1400/25=56 lei a cheltuit marti
