Answer:
AC = 23 so it be D
Step-by-step explanation:
plug AC = DF ---> 21x-19 = 3x+17
sub. 3x by both sides --> 18x-19 = 17
add 19 to both sides --> 18x = 36
divide both sides by 18, x = 2
plug x back into 21x-19 to find AC
21(2) - 19
42 - 19 = 23
