I need to know the answer

Answer:
x = 17
Step-by-step explanation:
-1 is the same as minus-ing it by 1.
10 + x - 1 = 26.
10 + 16 - 1 = 25, so it must not be x = 16.
x = 17. lets try it.
10 + 17 - 1 = 26!!