Final answer:
After solving the given equations for s and t, we find s = 3/7 and t = 1/3. Subtracting t from s, or 3/7 - 1/3, we get 2/21 as the value of s-t.
Step-by-step explanation:
The student's question requires solving two simple equations to find the values of s and t, and then compute the value of s-t. From the given equations 3/s=7 and 4/t=12, we can solve for s and t by rearranging the equations:
After simplifying, we find that s equals to 3/7 and t equals to 1/3. Finally, we calculate the value of s-t which is 3/7 - 1/3. This can be done by finding a common denominator, which is 21, leading to (9-7)/21 = 2/21. Hence, the value of s-t is 2/21.