How do you evaluate #-\frac { 9} { 10} + ( - \frac { 4} { 5} )#?

2 Answers
Feb 8, 2017

#-9/10+(-4/5)=-17/10#

Explanation:

First, find a common denominator. Since, #2times5=10# then,

#4/5times1=4/5times2/2=(4times2)/(5times2)=8/10#

Then

#-9/10+(-4/5)=-9/10+(-8/10)#

Since both fractions are negative we can factor out #-1#

Then

#-9/10+(-8/10)=-1times(9+8)/10=-1times17/10=underline(-17/10)#

Feb 8, 2017

#-1 7/10#

Explanation:

#-9/10+(-4/5)#

#:.=-9/10-4/5#

#:.=((1 xx -9)-(2 xx4))/10#

#:.=(-9-8)/10#

#:.=-17/10#

#:.=-1 7/10#