I don't know how to get the answer, but i know the answer is 127.50.
Answer:
i) 28 - 30i
ii) 36 + 28i
Step-by-step explanation:
i) x = 6 + i ⇒2x = 2(6 + i) = 12 + 2i
z = 4 - 8i ⇒ 4z = 4(4 - 8i) = 16 - 32i
2x + 4z = (12 + 2i) + (16 - 32i) = 28 - 30i
ii) w = -1 + 5i and z = 4 - 8i
w × z = (-1 + 5i)(4 - 8i) = -4 + 8i + 20i - 40
⇒collect like terms
w × z = -4 + 28i - 40
∵ 
∴w × z = -4 + 28i - 40(-1) = -4 + 28i + 40 = 36 + 28i
12% error. To find out subtract the difference between the estimate and the actual amount sold and divide the difference by the estamite.
For this case we have:
By trigonometric property we have:

Where:

Substituting:

Clearing x we have:

Thus, the equation is: 
Answer:
