How do you solve by substitution #d + e = 2# and #d - e = 4#?

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Answer 1 · 2015-06-05T23:41:00

Subtract #e# from both sides of the first equation to get:

#d = 2 - e#

Then substitute this in the second equation to get:

#4 = d - e = (2 - e) - e = 2 - 2e#

Add #2e# to both sides to get:

#2e+4 = 2#

Subtract #4# from both sides to get:

#2e = -2#

Divide both sides by #2# to get:

#e = -1#

Then

#d = 2 - e = 2 - (-1) = 2+1 = 3#