Answer:
Should be 39 years.
there is 12 inches in a foot. and if the tree grows 4 inches every year, then in 3 years the tree would be 1 foot. 13 x 3 = 39, thus proving that in 39 years, it will be 13 feet tall. I may be wrong but this sounds correct.
Answer: 36 degrees
Step-by-step explanation:
subtract 5 from 30=25
add 11 to 25
25+11=36
Half one is 1/2;
half three is 3/2;
Thus, if f(x) represents annual growth, f(x)/2 shows it every half-year, like this:

Written in plain text: f(x)=15/2*2^x
Eighths and their multiples are common fractions which I recommend memorizing, but to actually solve this, you use the literal meaning of a fraction and divide 5 by 8. See the long-division below (it was surprisingly difficult to type, so I hope it helps!).
To round 0.625 to the nearest hundredth, we go to the second decimal place, which is 5, so we round up to 0.63.
Find the factors from the roots, then multiply the factors together.
y
=
x
2
−
21
x
+
104