Debbie

Grade 9

Question:  20-(9+4)x7=?
Possible answer -71 or 49?

Thank-you

Hi Debbie,

In order to ensure that we all mean the same thing when we write this kind of expression there is an order of operations that everyone agrees to follow. First you evaluate anything inside parentheses. Thus, in your example, first evaluate 9+4 to get 13. Hence the problem becomes

20-137

Next perform any divisions or multiplications. Here you have 137 which is 91, and hence the problem reduces to

20-91

Finally perform any addition and subtractions to get 20-91=-71. Hence a solution to the problem is

20 - (9 + 4) 7
= 20 - 13 7
= 20 - 91
= -71

Cheers,
Penny

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