Question

1.Daca 3a+b=79 si 6a+2b+3c=200,atunci valoarea numarului 9a+3b+c este egala cu:
a)251
b)252
c)255
d)215

Answer 1

6 a + 2 b + 3 c = 200

3 a  +  b            =  79

______________________ → adun sumele date

9 a + 3 b + 3c = 200 + 79 = 279

3 × ( 3 a + b ) + 3 c = 279

3 × 79 + 3 c = 279

237 + 3 c = 279

3 × c = 279 - 237

c = 42 : 3 ⇒   c = 14

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9 a + 3 b + c = 251

= 3 × ( 3 a + b ) + c =

= 3 × 79 + 14 =

= 237 + 14 =

= 251

Raspuns:   a)  251