Step-by-step explanation:
AB · BE = CB · BD Given
CB/BE = AB/BD Division Property of Equality
<ABC = <DBE Vertical angles are equal
ΔABC ≅ ΔDBE SAS Similarity Theorem
Hope it helps
Answer:
The number 10 is the base
Here is the equation:

Since both decimals are negative, the answer will be positive.
- Negative times Negative = Positive
Divide both sides by -3.9 to leave the variable alone:

r is equal to 4 → r = 4