Solve the system of equations by substitution method: x + 2y = 5 3x + 17y = 37

x + 2y = 5; 3x + 17y = 37 – from the first equation we express x through y;

x = 5 – 2y – substitute the expression (5 – 2y) instead of x in the second equation;

3 (5 – 2y) + 17y = 37;

15 – 6y + 17y = 37;

11y = 37-15;

11y = 22;

y = 22: 11;

y = 2 – find x, substituting for y the number 2 in x = 5 – 2y;

x = 5 – 2 * 2 = 5 – 4 = 1.

Answer. (12)