We cannot determine the cost of the tiles from the given information, so the question cannot be answered.
Answer: eight hundred ninety thousand, seven hundred four
5(4x - 10) + 10x = 4(2x - 3) + 2(x - 4)
20x - 50 + 10x = 8x - 12 + 2x - 8
30x - 50 = 10x - 20
30x - 10x = -20 + 50
20x = 30
x = 3/2 <==
This is really a long way to go to make something complicated
out of something simple. The last choice does the job.
cos(180) = -1
sin(180) = 0
So 4 [cos(180) + i sin(180) ]
= 4 [ -1 + i (0) ]
= -4 yay!
