What does e equal?
Always remember the simple rule of P.E.M.D.A.S. Known as the order of operations.
If you use this method start from the left to the right...
Parenthesis | Exponents | Multiplication | Division | Addition | Subtraction
An easy way to remember it is "(P)lease (e)xcuse (m)y (d)ear (a)unt (s)ally."
Hope this helps!
I will try and give you a step by step solution.
8e + 3(5-e) = 10
first distribute the 3(5-e) this gives you
8e + 15 - 3e = 10
Then simplyify to
5e + 15 = 10
Now isolate the e on the left side by subtracting 15 from both sides
5e = -5
Now divide by 5
e = -1