Question 175231
The first step is to distribute through on both sides.  So
-2(1+5a) = -4+6(a+3) becomes

-2(1) + -2(5a) = -4 + 6a + 6(3)

-2 - 10a = -4 + 6a + 18

-2 - 10a = 14 + 6a

Next, we need to combine the "a" terms and combine the constants.  So, add 10a to both sides, and subtract 14 from both sides.

-16 = 16a

Lastly, dividing by 16 on both sides yields a = -1.
Don't forget to always check your work!