Answer: 
Step-by-step explanation:
To find the inverse of a function replace f(x) with x and the original x with y

Now we can solve for y
Square both sides so we can cancel out the root

Now subtract 7 from both sides

Now replace y with the inverse of f(x), 
The max of Lauren's age --> the minimum of the others' ages, 1, 2 & 3
4*avg = 4*9 = 36
36 - (1+2+3) = 30
Lauren is 30 yrs of age, or younger.
Answer:
The tax rate was 0.8%
Step-by-step explanation:
Set up an equation:
x = tax rate
1000/125000 = x/100
Cross multiply:
1000 × 100 = 125000 × x
100000 = 125000x
0.8 = x
Check your work:
1000/125000 = 0.8/100
0.008 = 0.008
Correct!
Another way to check your work:
1000 × 100 = 125000 × 0.8
100000 = 100000
Correct!