Answer: 1. r=3 2. 
Step-by-step explanation:
1. Given equation : 
To solve this for r , we add 8 and subtracting r on both sides , we get

Now, combine like terms, we get

Dividing 6 on both sides , we get

2. Given equation : 
To solve for U , we first multiply E on both sides , we get

Now, divide 3 on both sides , we get
