How do you solve #15= - d + 20#?

1 Answer
Sep 24, 2016

Answer:

#d = 5#

Explanation:

Subtract #20# from both sides. This gets us the equation

#15 - 20 = - d + 20 - 20#

#-5=-d#

You then can multiply both sides by #-1# to get

#-5 * (-1) = -d * (-1)#

#5=d#

The other way to do this is to add #d# to both sides to get

#15+d=20#

and then subtract #15# from both sides to get

#5=d#

Either way, both of these work.