Question 268467
[4 - (3c - 1)][6 - ( 3c - 1)]
Removing the brackets changes the sign inside the bracket
[4 - 3c + 1)][6 - 3c + 1)]
(5 - 3c)(7 - 3c)
FOIL
35 - 15c - 21c + 9c^2
:
9c^2 - 36c + 35 = 0
Factors to
(3c - 5)(3c - 7) = 0
Two solutions
3c = 5
c = {{{5/3}}}
and
3c = 7
c = {{{7/3}}}