Whats the value what ever it is its divided by three
Using the variable x for the unknown number,
20 - (x + 4) = 6
is your answer!
Hope I helped :)

Step-by-step explanation:
Since we have given that
Time taken by steamboat makes the trip=5 hours
Time taken by yacht makes the trip =2.5 hours
Since we have also given that
the yacht is 20 knots faster than the steamboat,
So let the speed of steamboat be x
Let the speed of yacht be x+20
Now, we have given that both boats will travel the same distance ,
So,

Hence,

The starting weight of the radioactive isotope = 96 grams
Weight after one hour is half of the starting weight. So the weight of the radioactive isotope after 1 hour = 48 grams
After 2 hours the weight is half as compared to the weight after previous hour. So weight after 2 hours = 24 grams.
This means, after every hour the weight is being halved. The half life of radioactive isotope is one hour.
Since after every hour, the weight is being halved, the weight of the isotope can be modeled by an exponential equation.
So,
Initial Weight = W₁ = 96
Change factor = 1/2 = 0.5
The general equation of the sequence will be:

Here t represents the number of hours. Using various values of t we can find the weight of the radioactive isotope at that time.
We can plot the sequence using the above equation. The graph is attached below.
2L+2W=157.5
L=W-30
2(W-30)+2W=157.5
2W-60+2W=157.5
+60 +60
4w=217.5
W=54.4(.37 rounded to nearest tenth)
L=24.4