Answer: -30
Let's call the original number "x". Then, we can write the equation as follows:
-3/10 x + 1 = 10
To find the original number, we can isolate x by subtracting 1 from both sides and then multiplying both sides by 10/3:
-3/10 x = 9
x = (9 * 10)/(-3)
x = -30
So, the original number is -30.