Respuesta :

Estimation:

23 --> rounded to 20
71 --> rounded to 70
70 + 20 = 90. I rounded both numbers down so the exact sum must be only a little greater than my estimate.
23 would be 20

71 would be 70

20 + 70 = 90


The actual answer is:

21 + 71 = 92


Hope this helps!

Bye :)