Rearrange as
1 a^3
_____ + _______ = 7
a^3+ 7 a^3 + 7
1 + a^3
______ = 7 cross-multiply
a^3 + 7
1 + a^3 = 7 ( a^3 + 7)
a^3 + 1 = 7a^3 + 49 subtract 49, a^3 from both sides
-48 = 6 a^3 divide both sides by 6
-8 = a^3 take the cube oot of both sides
-2 = a
+113 
