Explain howyou wouldestimateto subtract 189 from 643

I would estimate 643 - 189 by rounding 643 to the tens place and 189 to the hundreds place.

643 => 640

189 => 200

Now you can subtract 200 from 640.

640 - 200 = 440

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 !