First, distribute 2/5 to both terms inside the parentheses:
(2/5)(10x) + (2/5)(15) = 26
Now simplify:
4x + 6 = 26
Next, subtract 6 from both sides of the equation:
4x = 26 - 6
4x = 20
Finally, divide both sides of the equation by 4 to solve for x:
x = 20/4
x = 5