Plz answer-patti is using mental math to evaluate the expression (70 + 12.8 + 30)+ 6.1. she recognizes that the expression will be easier to simplify if she can combine 70 and 30 before she works with the other numbers. how do the properties of operations allow patti to take that approach?

COMMUTATIVE PROPERTY OF ADDITION.

Step-by-step explanation:

Given Expression is ( 70 + 12.8 + 30 ) + 6.1

Yes the expression will be easier to simplify if she can combine 70 and 30 before works with the other numbers.

She can only do this if she exchanges position of 12.8 and 30 in the bracket.

And this can be done using COMMUTATIVE PROPERTY OF ADDITION.

COMMUTATIVE PROPERTY OF ADDITION : This property allows us to reorder the position of numbers.

a + b = b + a

After using this property she can add 70 & 30 and then simplify the expression  further.

Consider,

( 70 + 12.8 + 30 ) + 6.1

using mentioned property we get,

= ( 70 + 30 + 12.8 ) + 6.1

= ( 100 + 12.8 ) + 6.1

= 112.8 + 6.1

= 118.9

it is b)

hope this : )

step-by-step explanation: