How do you evaluate #8-20+(-39)-(-12)+13-48#?

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Answer 1 · 2018-03-06T01:40:53

#color(blue)(-74)#

#8 - 20 + (-39) - (-12) + 13 - 48#

#=> 8 - 20 - 39 + 12 + 13 - 48# Removing the braces.

#=> 8 + 12 + 13 - 20 - 39 - 48# Rearranging terms.

#=> (8 + 12 + 13 ) - (20 + 39 + 48)# Grouping terms according to sign.

#=> 33 - 107 = - 74#

Answer 2 · 2018-03-06T01:50:09

-74

A #-#number and #+#number make #-#.
A #-#number and #-#number make #+#.
A #+#number and #+#number make #+#.

Knowing these rules, we can simplify the equation.
#8 − 20 + ( − 39 ) − ( − 12 ) + 13 − 48 ->#
#8 − 20 − 39 + 12 + 13 − 48#

Following PEMDAS, add first.
#8 − 20 − 39 + (12 + 13) − 48 ->#
#8 − 20 − 39 + 25 − 48#

Subtract.
#8 − 20 − 39 + 25 − 48 ->#
#-12 − 39 + 25 − 48 ->#
#-51 + 25 − 48 ->#
#-99 + 25#

Add.
#-99 + 25 = -74#