In this equation what is strange is probably using the letter a as the unknown, but this is a matter of choice we could have calle y or z for that matter. Then we will treat it ans any other equation and solve it.
-11 -5a = 6(5a+4)
-11 -5a= 30a + 24
-11 - 24 = 30a + 5a (placing the unknown a in the rght side and the numbers in the left to solve the equation)
