Question

ma ajutati va rog repede

Answer 1

a = 3c
a = n - 7  =>  n = a + 7  =>  n = 3c + 7
a + n + c = 77
3c + 3c + 7 + c = 77
7c = 77 - 7
7c = 70
c = 70 : 7 = 10
a = 3c = 30
n = 3c + 7 = 37
Cristina are 10, Andreea are 30 si Nicoleta are 37.

Answer 2

A= /---/---/---/
C=/---/
                   +7
N=/---/---/---/.../

A+C+N=77
77-7=70 ( ELIMINAM PLUSURILE )
70:7=10 ( CRISTINA )
10X3=30 ( ANDREEA )
10X3+7=37 ( NICOLETA )