Enter into calculator if possible, it is C by the way :DDDD
Answer:
The slope will be the same for a straight line no matter which two points you pick as you know. All you need to do is to calculate the difference in the y coordinates of the 2 points and divide that by the difference of the x coordinates of the points(rise over run). That will give you the slope.
Answer:
0.08*x + 0.09*(9000-x) = 750 dollars
0.08x + 810 - 0.09x = 750
-0.01x = 750 - 810 = -60 ====> x = %28-60%29%2F%28-0.01%29 = 6000.
Answer. $6000 was invested at 8%. The rest 9000-6000 = 3000 dollars were invested at 9%.
Check. 0.08*6000 + 0.09*3000 = 480 + 270 = 750 dollars. ! Correct !
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hope this help