The answer is 4/35 or 0.11428571428 as a decimal.
Step 1: Simplify 12/15 to 4/5
Step 2: 4/5 x 1/7
Step 3: 4 x 1 / 1 x 7
Step 4: Simplify (which will give you your answer.
Let me know if I helped you! Have a great day :)