Answer:
The unknown number here is 5.75.
Step-by-step explanation:
Given,
The sum of 6 and 4 times a number is 29.
We need to find the number.
i.e.,

Thus, the number is 5.75.
The addition of 6 and four times of 5.75 will leads to 29.
Therefore, the unknown number will be 5.75.