[tex]4a + 3b = 28[/tex]
[tex]4a = 28 - 3b[/tex]
[tex]a = \frac{28 - 3b}{4} [/tex]
[tex]3a + 4b = 35[/tex]
[tex]3 \times \frac{28 - 3b}{4} + 4b = 35[/tex]
[tex] \frac{3(28 - 3b)}{4} + 4b = 35 \: | \times 4[/tex]
[tex]3(28 - 3b) + 16b = 140[/tex]
[tex]84 - 9b + 16b = 140[/tex]
[tex] - 9b + 16b = 140 - 84[/tex]
[tex]7b = 56 \: | \div 7[/tex]
[tex]b = 8 \: lei[/tex]
[tex]a = \frac{28 - 3b}{4} [/tex]
[tex]a = \frac{28 - 3 \times 8}{4} [/tex]
[tex]a = \frac{28 - 24}{4} [/tex]
[tex]a = \frac{4}{4} [/tex]
[tex]a = 1 \: leu[/tex]
