If x is the acceptable weight, the difference between the acceptable weight x, and 430 cannot exceed 20.
We express this as |x-430|≤20, in absolute value notation.
we have the following 2 cases
x can be smaller than 430, in this case: 430-x≤20, that is 410≤x
x can be greater than 430, in this case: x-430≤20, that is x≤450
Solution: 410≤x≤450