Question

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Answer 1

please, is your second equation this?
-d+e=-5

Answer 2

from that equation we have:
e=-5+d,
I substitute that in your first equation:
d+(-5+d)=15
so:
2d-5=15
2d=15+5
2d=20
d=10,
noe I return to this equation: e=-5+d
I substitute for d:
e=-5+10=5
so your answer is:
(d,e)=(10,5)

Answer 3

do you agree?

Answer 4

thank you!