3C 153 is a Seyfert galaxy located in the constellation Auriga.
I assume when you mean brightness, you mean apparent magnitude as opposed to absolute magnitude. The quasar 3C 273 has an apparent magnitude of about 12.8 whereas the brightest galaxy - the Large Magellanic Cloud has an apparent magnitude of 0.9. However, in absolute magnitudes, 3C 273 has an absolute magnitude of about -26.7 very similar to our own Sun.
3c+6=18 3c+6-6=18-6 3c=12 3c÷3=12÷3 c=4
3c-7 = -4
2y-3c = -1
The solution (not sum) to the equation 21 = 3c + 6 is as follows:21 = 3c + 621 - 6 = 3c + 6 - 615 = 3c3c = 153c/3 = 21/3c = 7
42 is a multiple of 3. 42c is a multiple of 3c. 42 can be but is not necessarily a multiple of 3c.
3c x 8e = 24
Legend , see related link and 3c defined .
(8 - 3c)(8 + 3c)
3c-d
It is: -28+21c = -7(4-3c)
2c-10