Solve by the linear combination method (with or without multiplication).

Question

x + y = 50
0.05x + 0.06y = 2.8

Answer 1

Eq1: X + Y = 50
Eq2: 0.05X + 0.06Y = 2.8
Multiply Eq1 by -0.05:
-0.05X - 0.05Y = -2.5
+0.05X + 0.06Y = 2.8
Add the Eqs:
0.01Y = 0.3,
Y = 30.

Substitute 30 for y in Eq1:
X + 30 = 50,
X = 20.

Solution Set = (20 , 30).

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Answer 2

x+9y=14
-2+y=10