Answer: A
Explanation: multiply 128 by .85
Let X = the 29% alloy and Y = the 60% alloy.
They want a total of 80kg, so you have X +Y = 80
Rewrite that to get X = 80-Y
You also want 0.20X + 0.60Y = 0.52(80)
Replace X with 80-y:
0.20(80-y) + 0.60y = 0.52(80)
Simplify:
16 - 0.20y + 0.60y = 41.6
Combine like terms:
16 +0.40y = 41.6
Subtract 16 from each side:
0.40y = 25.6
Divide both sides by 0.40
y = 25.6 / 0.40
y = 64
Now you have Y replace y with 80 in X = 80-Y
X = 80 - 64
X = 16
They need 64 Kg of the 60% alloy and 16 Kg of the 20% alloy.
theta is in the fourth quadrant where the cosine is positive.
the third side in the triangle = sqrt (4 - 2) = sqrt2
So sin theta = -sqrt2/2 = Second choice (negative because sine is negative in 4th quadrant)
tan theta = - sqrt2 / sqrt2 = -1
By combining like terms, the answer is a
