2step equation:

-17 + b/8 =13
7 (c-12)= -21
-3 + p/7 = -5
46= -6t - 8

-17 + b/8 = 13
+17             +17
b/8 = 30
x8     x8
b = 240
(-17 + 240/8 = 13   =   -17 + 30 = 13    =   13 = 13)

7(c - 12) = -21
7c - 84 = -21
     +84     +84
7c = 63
/7     /7
c = 9
(7(9-12) = -21    =   63 - 84 = -21   =   -21 = -21)

-3 + P/7 = -5
+3             +3
P/7 = -2
x7      x7
P = -14
(-3 + -14/7 = -5     =   -3 + -2  = -5    =    -5 = -5)

46 = -6t - 8
+8          +8
54 = -6t
/-6     /-6
-9 = t
(46 = -6(-9) - 8    =    46 = 54 - 8      =     46 = 46)

The 8th term is 512