Answer:
sister = 6 years
John=18 years
Step-by-step explanation:
A(S) + 12 = 3 * A(S), subtracting A(S) from both sides one gets 12 = 2 * A(S). Now dividing both sides by 2 we get A(S) = 12/2 = 6 . Therefore, the age of the sister is 6 years when her brother John is three times as old, that is 18 years.
Answer:
a(7)=3645
Step-by-step explanation:
you have :
f(1) =a= 5
and from recursive rule: f(n) = r · f(n − 1) and f(n) = 3 · f(n − 1)
So r=3
then
a(n)=a*r^(n-1)
a(7)=5*3^(7-1)
a(7)=5*3^6=3645
<em>hope this helps</em>
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Answer:

Step-by-step explanation:
To solve the equation, isolate x. Whatever you do to isolate x one on side, you must do to the other.
1) Multiply both sides by 9 to get rid of the fractions.

2) Distribute the 3 to 8x and 15. Then, combine like terms.
3) Move the 66 to the other side, subtracting 18 by 66, then divide each side by 20 to finally isolate x.

Thus,
.