Answer:

Step-by-step explanation:
we know that
The simple interest formula is equal to
where
I is the Final Interest Value
P is the Principal amount of money to be invested
r is the rate of interest
t is Number of Time Periods
in this problem we have
substitute in the formula above
solve for t

The next number would be 8+13 = 21
Don't look at this comment.. I messed up the first time so, yeah.
Answer:
x = 4.6439
Step-by-step explanation:
2^x =25
Take the log of each side
log 2^x = log 25
We know that log a^b = b log a
x log 2 = log 25
Divide each side by log 2
x = log 25 / log 2
x =4.643856
Rounding to 4 decimal places
x = 4.6439
This question is obviosly missing an ending but, I bet you will have to divide.