Based on the given information, the ratio of x to y is 2:7. This means that for every 2 units of x, there are 7 units of y. Since we are asked to find the angle of x, we can assume that x and y are sides of a right triangle. In a right triangle, the angle opposite the shorter side (x) is always smaller than the angle opposite the longer side (y). Therefore, the angle of x must be smaller than 90 degrees. Among the options provided, the only angle that is smaller than 90 degrees is 40 degrees. Hence, the correct answer is 40 degrees.