In high utility itemset mining, there are usually two types of numeric values : purchased quantities and unit profit values. For example, a customer can buy 3 apples, and each apple yield 5 $ profit.
In your example database, you have a single table. So I assume that each item is associate with some amount of money for example. So your transaction:
T1: A (10) B(20) C(10) D (15)
means that item A was sold and generated a 10 $ profit, B was sold with a 20 $ profit etc.
How we calculate the utility? If you want to calculate the utility of AD, you would make the sum of the profit of AD in all transactions where A and D appear together. So, here for example, A and D appears in transactions T1, T2, T3 and T4.
Thus the utility of AD is 10 + 15 (the profit of AD in T1) + 25 + 12 (the profit of AD in T2) + 15 + 18 (the profit of AD in T3) + 20 + 27 (the profit of AD in T4).
This is the main idea. Actually, I wrote a blog post that explain that with another example, and some pictures:
You can read it.
For the other part of your question, it depends what kind of rules you want to find. If you want to find sequential rules (rules with time), you can check this paper:
Zida, S., Fournier-Viger, P., Wu, C.-W., Lin, J. C. W., Tseng, V.S., (2015). Efficient Mining of High Utility Sequential Rules
. Proc. 11th Intern. Conference on Machine Learning and Data Mining (MLDM 2015). Springer, LNAI 9166, pp. 157-171.