How do you solve #5d - 6= 3d + 9#?

3 Answers
Sep 13, 2017

Subtract #3d# from both sides then add #6# to both sides,
then divide by the coefficient of the variable to get #d=7 1/2#

Explanation:

Given
#color(white)("XXX")5d-6=3d+9#

By subtracting #3d# from both sides we can remove any term containing a variable from the right side:
#color(white)("XXX")5d-6color(blue)(-3d)=3d+9color(blue)(-3d)#

#color(white)("XXX")2d-6=9#
Now, if we add #6# to both sides we can remove any constant term from the left side:
#color(white)("XXX")2d-6color(blue)(+6)=9color(blue)(+6)#

#color(white)("XXX")2d=15#

Finally dividing both sides by #2# reduces the left side to a unit variable:
#color(white)("XXX")2dcolor(blue)(div 2)=15color(blue)(div 2)#

#color(white)("XXX")d=7 1/2#

Sep 13, 2017

#5d-3d=6+9#
#2d=15#
#d=15/2#
#d=7.5#

Sep 13, 2017

#7.5#

Explanation:

#5d-6=3d+9#
First, we will remove #3d# from both sides.
#5d-6(-3d) = 3d+9(-3d)#
The #-3d# in the brackets represent what we will remove.
That will equal #2d-6=9#
#9+6=15#
#15=2d#
#1d=15/2=7.5#
Solved!