A population of mice, some with light-colored fur and some with dark-colored fur are introduced into a field with dark soil. A few generations later, the majority of the mice have dark-colored fur. Which of the following best explains this change? * Light-colored mice can run faster.
Dark-colored mice have fewer offspring.
Light-colored mice have changed color over generations.
Dark-colored mice are better able to hide from their predators.

Dark-colored mice are better able to hide from predators.

Explanation:

If all of the light mice are eaten, then there are none left to pass on the light-furred gene, meaning that there would be no offspring without dark fur.

so here we go

atomic mass

239 + 1 = y + 134 + 3 combine like terms

240 = y + 137             subtract 137 from both terms

240 - 137 = y

103 = y

atomic number

94 = z +54 + 0

94 = z + 54               subtract 54 from both sides.

40 = z

answer