Answer:
-6
Step-by-step explanation:
Answer:

Step-by-step explanation:
we know that


Let
x ------> new battery life
The equation that represent this situation is

convert to mixed number

Answer:
standard form : 2x + y = -2
2a + 2b = c
Subtract 2a from both sides
2b = -2a + c
Divide both sides by 2
b = -a + (c/2)