Question 21A student starts with the two numbers 3 and 5. Each operation replaces the two numbers by their sum and their positive difference. After 50 operations, what two numbers remain? $3^{25}$ and $5^{25}$$3^{50}$ and $5^{50}$$2\cdot3^{25}$ and $2\cdot5^{25}$$3\cdot2^{25}$ and $5\cdot2^{25}$None of the previous choices