Question

8.21+3.89=______+4.00

Answer 1

You know that on the left : 8,21 + 3,89 = 12,1

So, we can guess that on the right the calcul must give 12,1 also.

So 12,1 - 4,00 = 8,1.

In short, the answer would be : 8,21 + 3,89 = 8,1 + 4,00.

Hope this helps !

Photon

Answer 2

8.21+3.89=____+4.00
12.10=____+4.00
-4.00 both sides

8.10