Răspuns:
1. a= 5×b
b= c:3
c= 2× d
d= 99
c=2×99=198
b= 198:3=66
a= 5 × 66=330
3. e=90:5=18
d=18:2=9
c=9+ 51 =60
b=60:3 =20
a=20+15 = 35
