Nine tokens are black on one side and white on the another initially four tokens have the blackside upwards in each turn tell the least number of turns yo need to have all tokens showing the same colour

2

Step-by-step explanation:

Let us name the white chips "W" and the black ones "B". If there are 9 tiles and 4 are in black then the rest, that is 5, in white, like this:

B-B-B-B-W-W-W-W-W

First movement, in turn we can flip 3 tiles, in this case we flip two blacks and one white, it would look like this:

W-W-B-B-B-W-W-W-W

The second movement is to turn the 3 black ones and thus they would all be blank

W-W-W-W-W-W-W-W-W

This means that, the smallest number of movements is 2.

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 !