9=3^2
3^(2x)=(3^2)^(3x-4)
3^(2x)=3^(6x-8)
2x=6x-8
0=4x-8
8=4x
2=x
112 dallors interest beca0.02x + 0.04(800) = 112 0.02x + 0.04(x + 800) = 112 0.04x + 0.02(x + 800) = 112 use
Answer:
11 years old
Step-by-step explanation:
If four brothers have the average age 6, then the sum of their ages is

years.
Let x years be the age of sister. If four brothers and their sister have the average age 7, then

Multiply this equation by 5:

The sister is 11 years old.