Let that certain number be 'n'
50% (n) = 39
50% ⇒ 0.5
0.5 (n) = 39
Divide both sides by 0.5
0.5n = 39
/0.5 /0.5
n = 78.
So that certain number is actually <em><u>78! :)</u></em>
CROSS CHECK:
50% of 78
0.5 × 78
= 39
Hope this helps! :)
Answer : Distance between the ships to the nearest miles = 106.03 ≈ 106 mi.
Explanation :
Since we have shown in the figure below :
a=70 mi.
b=52 mi.
c=x mi.

So, we use the cosine rule , which states that

So, c = x= 106.03 mi.
Hence, distance between the ships to the nearest miles = 106.03 ≈ 106 mi.