Answer to Question #13213 in Algebra for regina

Question

0.04x + 0.02y = 78
x + y = 2800
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solve the system and you get your answers
sum at 4% = x
sum at 2% = y

Answer 1

0.04x + 0.02y = 78 (1)
x + y = 2800& (2)
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(2) ==>
x = 2800 - y
(1):
0.04(2800 - y) + 0.02y = 78 ==>
112 - 0.04y + 0.02y = 78 ==>
-0.02y = -34 ==>
y = 1700.
So,
x = 2800 - 1700 = 1100.