Answer:
f(13) = -57
Explanation:
We are given the function f(x) = 3(-2x + 7) and asked to find the value at f(13). Substitution means to replace an unknown value with a known one in order to solve a problem. We can do this by substituting the value of 13 for the x-value in the function.
f(13) = 3(-2(13) + 7)
f(13) = 3(-26 + 7)
f(13) = 3(-19)
f(13) = -57
Therefore, because this question is asking us to find only the value at f(13), we have determined that f(13) = -57.