The correct answer is $\frac{9}{5}$ . Multiplying the first equation in the given system by $2$ yields $10 x + 28 y = 90$ . Subtracting the second equation in the given system, $10 x + 7 y = 27$ , from $10 x + 28 y = 90$ yields $(10 x + 28 y) - (10 x + 7 y) = 90 - 27$ , which is equivalent to $10 x + 28 y - 10 x - 7 y = 63$ , or $21 y equals 63$ . Dividing both sides of this equation by $21$ yields $y equals 3$ . The value of $x$ can be found by substituting $3$ for $y$ in either of the two given equations. Substituting $3$ for $y$ in the equation $10 x + 7 y = 27$ yields $10 x + 7 (3) = 27$ , or $10 x + 21 = 27$ . Subtracting $21$ from both sides of this equation yields $10 x equals 6$ . Dividing both sides of this equation by $10$ yields $x = \frac{6}{10}$ , or $x = \frac{3}{5}$ . Therefore, the value of $x y$ is $left parenthesis three fifths right parenthesis left parenthesis 3 right parenthesis$ , or $\frac{9}{5}$ . Note that 9/5 and 1.8 are examples of ways to enter a correct answer.