а)

[tex]\displaystyle\bf\\\left \{ {{2x + 2y = 12} \atop {3x - 5y = 5 }} \right. \\ \displaystyle\bf\\\left \{ {{x + y = 6} \atop {3x - 5y = 5 }} \right. \\ \displaystyle\bf\\\left \{ {{x = 6- y} \atop {3(6 - y) - 5y = 5 }} \right. \\ \\ 18 - 3y - 5y = 5 \\ - 8y = 5 - 18 \\ - 8y = -13\\ y = \frac{13}{8} \\ y = 1 \frac{5}{8} \\ \\ x = 6 - 1 \frac{5}{8} \\ x = 5 \frac{8}{8} - 1 \frac{5}{8} \\ x = 4 \frac{3}{8} [/tex]

Ответ: ( 4 3/8 ; 1 5/8 )

б)

[tex]\displaystyle\bf\\\left \{ {{3x - 2y = 3} \atop {2x + 3y = 15 }} \right. \\ \displaystyle\bf\\\left \{ {{2y = 3x - 3 \: \: | \div 2 } \atop {2x + 3y = 15 }} \right. \\ \displaystyle\bf\\\left \{ {{y = 1.5x - 1.5} \atop {2x + 3(1.5x - 1.5) = 15 }} \right. \\ \\ 2x + 4.5x - 4.5 = 15 \\ 6.5x = 15 + 4.5 \\ 6.5x = 19.5 \\ x = 19.5 \div 6.5 \\ x = 3 \\ \\ y = 1.5 \times 3 - 1.5 \\ y = 4.5 - 1.5 \\ y = 3[/tex]

Ответ: ( 3 ; 3 )