Answers

2016-06-26T10:54:11+08:00
x+y=19
+
x-y=15
_______
2x = 34

2x/2 = 34/2

x=17

x+y=19
17+y=19
y=19-17
y=2

x2-y2
=(17)2 - (2)2
=34 - 4
=30
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