3. Solve, then choose the interval that contains the solution: \[ 221-7 x=185 \] solution is less than -10 solution is greater than 6 solution is between -5 and -10 solution is between 2 and 6

Step 1 ：Solve the equation 221-7x=185 for x. Subtract 221 from both sides of the equation to isolate the term -7x. Then, divide both sides by -7 to solve for x.

Step 2 ：The solution to the equation 221-7x=185 is approximately \(x = 5.14\).

Step 3 ：Determine which interval this solution falls into. The given intervals are less than -10, greater than 6, between -5 and -10, and between 2 and 6.

Step 4 ：The solution to the equation 221-7x=185, which is approximately 5.14, falls into the interval (2, 6).

Step 5 ：Final Answer: The solution is in the interval \(\boxed{(2, 6)}\).