-7 = [tex] \frac{e}{3} [/tex] + 14
take 14 to the other side
-7 -(14) = [tex] \frac{e}{3} [/tex]
-21 = [tex] \frac{e}{3} [/tex]
Multiply by 3 on either sides to isolate e and to find a value
-21 × 3 = [tex] \frac{e}{3} [/tex] × 3
3 and 3 cancels out
-63 = e