Answer:
44.75
I believe
Let's go:
[tex]\frac{21}{36} = \frac{3x + 1}{6x - 6} \\\\ 36(3x + 1) = 21(6x - 6) \\\ 108x + 36 = 126x - 126 \\\ 126x - 108x = 36 + 126 \\\ 18x = 162 \\\ x = 9[/tex]
I hope I helped you.