Answer:
To sum consecutive numbers we use the formula:
n * (n+1) / 2
1 through 55 = (55 * 56) / 2 = 1,540
1 through 9 = (9 * 10) / 2 = 45
10 through 55 = 1,540 -45 = 1,495
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EDITED
Gee, it seems I added ALL numbers from 10 through 55
ALL ODD numbers from 10 through 55 sum to
759
Step-by-step explanation:
They would be parallel lines
Distance<-------------300--------------><-------------------x----------------->
⊕---------------------------------⊕--------------------------------------⊕ Express Freight Overtaking point
Speed 55 speed 30
Let x be the distance travelled by Freight until the point of overtaking
Time = Distance/Speed, then:
Time (freight) = Distance (fright)/Speed (freight) And
Time (Express) = Distance (Express)/Speed (Express).
Now plug in the relative number:
Time (freight) = x/30 and Time (express) = (x+300)/55. But note that both times are equal, then:
x/30 = (x+300)/55 OR (x÷30 = (x+300)÷55) [Answer C]
Now let's find the distance x. Cross multiplication;
55x= 30(300+x) →55x = 9,000 + 30x
55x - 30x = 9,000 → 25x = 9,000 and x = 9,000/25 = 360 miles
Time needed for Freight to travel 360 m = 360/30= 12 Hours
Time needed for Express to travel (300+360) m = 660/55= 12 Hours
As you see, it's the same time of 12 hours
Don't forget that Distance = Speed x time or time = Distance/Speed, etc.
9/7n is the answer i am pretty sure
Answer: x=1
Step-by-step explanation:
4 (-x+4）=12
（-4x+16）=12
-4x+16-16 =12-16
-4x/-4 =-4/-4
x=1
I don't know if this is right, please let me know if it is wrong ο(=•ω＜=)ρ⌒☆
