Question 1093436
Let some money be x. 
1) So the amount invested at 5% will be 0.05x.
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2) He invested the rest of the money at 7%. And the problem says this amount is 221 more than 2 times x: 0.07(2x+221)
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Put these two together:
0.05x + 0.07(2x+221) = 850.52
0.05x + 0.07(2x + 221) = 850.52
0.05x + 0.14x + 15.47 = 850.52
0.19x = 835.05
x = 4395 This is the amount invested at 5%
At 7%: (2*4395)+221 = 9011
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Let's check to see if I got you the right answer:
(0.05(4395)) + (0.07(9011)) = 850.52 Correct