Give an example to show that subtraction does not follow the associative rule

(6 - 2) - 1 = 4 - 1 = 3

6 - (2 - 1) = 6 - 1 = 5

The associative rule doesn't work for subtraction because you get different results when you move the parentheses.

problem:

f(x) = - 2/3x + 5; f(5/2)

substitute 5/2 in for x:

f(5/2) = -2/3(5/2) + 5

simplify the right side:

f(5/2) = -5/3 + 5

f(5/2) = 10/3

f(5/2) = 10/3

i hope this !