a)
[tex]2x=3+y \ \ \rightarrow \ \ y = 2x-3\\4x=3y\\\\4x=3(2x-3)\\\\4x=6x-9\\\\4x-6x = -9\\\\-2x = -9 \ \ /:(-2)\\\\\underline{x = 4,5}\\\\y = 2x-3 = 2\cdot4,5 -3 = 9-3\\\\\underline{y = 6}\\\\\{x = 4,5\\\{y = 6[/tex]
b)
[tex]x+200\% x = y-5\\y - 60\%y = 3x\\\\x+2x=y-5 \ \ \rightarrow \ \ y = 3x+5\\y-0,6y = 3x\\\\3x+5-0,6(3x+5) = 3x\\\\3x+5-1,8x-3=3x\\\\-1,8x = 3-5\\\\-1,8x = -2\\\\-18x = -20 \ \ /:(-18)\\\\\underline{x = \frac{10}{9} = 1\frac{1}{9}}\\\\y = 3x+5 = 3\cdot\frac{10}{9}+5 = \frac{10}{3}+5\\\\\underline{y = 8\frac{1}{3}}\\\\\{x = 1\frac{1}{9}\\\{y = 8\frac{1}{3}[/tex]
