50% of a certain number is 39. what is the number?

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 78! :)

CROSS CHECK:

50% of 78

0.5 × 78

= 39

Hope this helps! :)