Algebra word problem?
Please show work if you can:
1) $5,900 is invested, part at 11% and part of it at 6%. For a certain year, the total yield is $509.00. How much was invested at each rate?
2) How much 75 octane and 90 octane gas is needed to make 15 gallons of 87 octane gas?
Comments
Let x = amount invested at 11%
1)...A1 = x(1.11)
2)...A2 = (5900 - x)(1.06)
2) ...A2 = 6254 - 1.06x
Total return = 5900 + 509 = 6409
A1 + A2 = 6409
3) 6409 = 1.11x + 6254 - 1.06x
155 = 1.05x
x = $147.62 invested at 11%
$361.38 invested at 6%
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Let x = gallons of 75 octane gas
75x + 90(15 - x) = 87*15
75x + 1350 - 90x = 1305
-15x = - 45
x = 3 gallons of 75 octane
12 gallons of 90 octane
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