Exponents

$3^{2c + 1} = 28 \times 3^c - 3^c$

$3^{2c + 1} = 27 \times 3^c$

$3^{2c + 1} = 3^3 \times 3^c$

$3^{2c+1} = 3^ {3 + c}$

$2c + 1 = 3 + c$

$c + 1 = 3$

$c = \color{brown}\boxed{2}$