53. A student was given a problem to solve, which required dividing the first of the given numbers by the second and multiplying the resulting quotient by a number, $\frac{2}{3}$ of which equals 4. However, the student proceeded as follows: from the first given number, he subtracted the second and added $\frac{2}{3}$ of 6 to the resulting difference. Despite this, the answer he obtained (10) was the same as the correct solution. What two numbers were given in the problem?
53. 15 and 9.