Penguins spent almost 75% of their lives in the sea .an emperor penguin in the wild has a lifespan about 18 years . about how many years does this penguin spend in the wild

First of all, in Mathematics, OF usually represents multiplication. And % means over 100. Anyway, the question basically means 75/100 multiplied by the lifespan. According to the question, the lifespan is 18 years. So that will be;
75/100 x 18
1350/100
13.5
  So your answer is 13.5 years. Hope i helped. Have a nice day.

1.4 x 10^5 have a nice day!