My brother is 4 years younger than my sister and 5 years older than me in 2 years. If I am 15 now how old will my sister be when
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Answer:
-3 - 1 = 4/9(-5 - 4)
Step-by-step Explanation:
Point-Slope form uses the formula y-y1=m(x-x1).
m is the slope, which they gave you, so you can substitute it into the formula:
y - y1 = 4/9(x - x1).
They also gave you a first point (-5, -3) So you can substitute the x and y of those into the formula as well.
-3 - y1 = 4/9(-5 - x1)
y1 and x1 are for another point. By drawing a graph and then using the rise and run of the slope (up 4 and over 9), you can get another point (as shown in the picture).
Substitute the x and y values of that point into the equation as well and you have your answer:
-3 - 1 = 4/9(-5 - 4)
City A is far from City B by 170 miles
Step-by-step explanation:
A railroad track runs parallel to a highway from City A to City B
- An express train and an automobile leave City A at the same time
- The train travels 85 mph
- The automobile travels at 50 mph
- The train arrives 1 hour and 24 minutes before the automobile arrives
We need to find how far is City A from City B
Assume that the distance from City A to City B is x mile
∵ Distance = Speed × Time
∴ Time =
∵ The speed of the train = 85 mph
∵ Distance between city A and city B = x miles
∴ The time for the train = hours
∵ The speed of the automobile = 50 mph
∵ Distance between city A and city B = x miles
∴ The time for the automobile = hours
The train takes time less because it travels by high speed
∵ The train arrives 1 hour and 24 minutes early then the automobile
- Change the time to hour only
∵ 1 hour = 60 minutes
∴ 24 minutes = hour
∴ 24 minutes = 0.4 hour
∴ The train arrives 1.4 hours early then the automobile
Now lets subtract the time of the train from the time of the automobile and equate the answer by 1.4
∵
- Multiply each numerator by the other denominator and multiply
the two denominators to make the two fraction a single fraction
∴
∴
- Multiply both sides by 4250 to cancel the denominator
∴ 35x = 5950
- Divide both sides by 35
∴ x = 170
City A is far from City B by 170 miles
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