Question

Exaercitiul 6,7,11,9,12.

Answer 1

6)a+1+a+3+a+5=75;b=a+1 c=a+3 d=a+5
3a+9=75
3a=66=>a=22
b=23 c=25 d=27
7)a+b=75
a-b=15=>a=15+b
15+b+b=75
2b=75-15=>2b=60=>b=30
===> a=15+30=>a=45
9)x-pret cărți
y-pret caiete
x=6 lei

y=4lei
5×6+3×4=30+12=42lei
11)Fiind a nr natural
[(a+12)+36]+6=51
[(a+12)+36]=45
a+12=45-36=>a+12=9=>a=-3
12)x-kg de fructe
y-sticle de apă minerală
x+2y=19/-x
x+4y=29/-x
5x+6y=?
-2y=-10=>y=5
x+10=19=> x=9
45+30=75