Question

5 kg de malai si 2 kg de zahar costa 102 lei ; 7 kg de malai costa cu 34 lei mai mult decât 4 kg de zahar. Aflati cit costa un kg de malai si cit costa un kg de zahar
Metoda substituiti

Answer 1

1Kg malai = m
1Kg zahar = z
7m = 4z + 34
5m + 2z = 102 |*7
35m + 14z = 714 | :5
7m + 2.8z = 142.8
4z + 34 + 2.8z = 142.8
6.8z + 34 = 142.8 |-34
6.8z = 108.8
z = 16
7m = 4*16 + 34
7m = 64 + 34
7m = 98
m = 14

Answer 2

7m = 4z + 34
5m + 2z = 102 /×7
35m + 14z = 714 / ÷5
7m + 2.8z = 142.8
4z + 34 + 2.8z = 142.8
6.8z + 34 = 142.8 /-34
6.8z = 108.8
z = 16.
7m = 4×16 + 34
7m = 64 + 34
7m = 98
m = 14