Explicație pas cu pas:
4. (n•3,6+40-10)÷3-1/4=88,5
(n•18/5+30)÷3=177/2+1/4
(18n/5+30)÷3=354/4+1/4
(18n/5+30)÷3=355/4
18n/5+30=355/4•3
18n/5+30=1065/4
18n/5=1065/4-120/4
18n/5=945/4
n=945/4•5/18=4725/72=1575/24=525/8
5.(a+b+c)/3=20
a+b=40
b+c=3a
40+c=60
c=20
a+3a=60
4a=60
a=15
b=60-(15+20)=60-35=25
b=25
