Final answer:
To solve the equation 210 = -5 (-7 - 5a) for a, distribute the -5, combine like terms, and then divide by the coefficient of a to find that a equals 7. The options provided do not match this correct answer.
Step-by-step explanation:
The student is asking to solve the equation 210 = -5 (-7 - 5a) for a. First, distribute the -5 inside the parentheses:
-5(-7) - 5(-5a) = 210
35 + 25a = 210
Next, subtract 35 from both sides of the equation:
25a = 210 - 35
25a = 175
Now, divide both sides by 25 to isolate a:
a = 175 / 25
a = 7
It appears there might have been a misunderstanding, as the options provided do not include a = 7, which is the correct answer based on the given equation.