Răspuns:
7. [tex]\left \{ {{a+b=40} \atop {5a-2b=144}} \right.[/tex] a= nr rasp corecte, b = nr rasp gresite
a= 40-b
5*(40-b) -2b= 144
200 -5b-2b=144 200-144= 7b b= 56:7= 8 b= 8 rasp gresite
a= 40-8=32 a= 32 rasp corecte
8. a+b =40 =>a=40-b
4a+1,5b=150 4*(40-b) +1,5b= 150
160 -4b+1,5b =150 160-150 = 4b-1,5b
10=2,5b b= 10:2,5 b= 4
a=40-4=36 a=36 dar 36*4 +1,5*4= 144+6=150
ca sa depaseasca trebuie sa fie 37 rasp corecte
37*4+1,5*4= 148+6=154 pct
