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Schach [20]
3 years ago
7

David canoes 20km downstream in 2.5 hours his return trip takes 4 hours find the rate of his current. A 1.5 km/h B 1 km/h C 0.5

km/h D 2.5 km/h
Mathematics
1 answer:
Art [367]3 years ago
5 0

Answer:

1.5 km/hour

Step-by-step explanation:

d is the David's speed in still water

c is the speed of the current

Going with the current, he travels d+c km per hour.

Going against the current, he travels d-c km per hour.

d+c = (20 km)/(2.5 hours) = 8 km/hour

d-c = (20 km)/(4 hours) = 5 km/hour

Add the equations to eliminate the c terms

d+c = 8

d-c = 5

----------

2d = 13

d = 6.5 km/hour

c = 8-d = 1.5 km/hour

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answer- 1

step by step explanation-

6-1 =5

two Ka half one

8 0
3 years ago
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Can someone help plz
olchik [2.2K]

Answer:

A.) 2x - 9x - 30 = -6

Step-by-step explanation:

hello !

to solve this system of equations, first, we substitute the equation y = 3x + 10 to the <em>y </em>variable in the equation 2x-3y = -6. Therefore, we get:

2x - 3(3x+10)=-6

now, we simplify by multiplying -3 to the variables inside the parenthesis, which, in short, is also called the distributive property. thus, we get:

2x - 9x - 30 = -6

4 0
3 years ago
how much water should be mixed with 6 gallons of 55% solution of sulfuric acid to make a 20% solution of sulfuric acid
nevsk [136]
Hello.

For all dilution problems use the dilution equation: 
<span>C1V1 = C2V2 </span>
<span>20*V1 = 6*55 </span>
<span>V1 = 6*55/20 </span>
<span>V1 = 16.5 gallons </span>
<span>The final volume must be 16.5 gallons </span>
<span>You must add 16.5 - 6 = 10.5 gallons water to be added.
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Have a nice day
6 0
3 years ago
A scale drawing of a school bus has a scale of 1/2 inch to 5feet. If the length of the school bus is 4 1/2 inches on the scale d
Sedaia [141]
Answer: actual length = 45 ft

Explanation:

Scale drawn:

1/2 inch = 5ft

Meaning that if the drawing scale is 0.5 inch then the actual bus would be 5ft.

If the length of the drawn school bus is 4 1/2 inches. We can write:

1/2 = 5
4 1/2 = x

=> x = (5 x 4 1/2)/1/2
Or x = (5 x 4.5)/0.5
x = 22.5/0.5
x = 45

Therefore the actual length of the bus is 45 ft

3 0
3 years ago
A man drove his car at 80km per hr for 1 and a quarter hrs .He rested for 45mins and then covered 240km, at the same time. Calcu
prisoha [69]

Answer:

Probably 128 km/h, but maybe 98.5 km/h. See below.

Step-by-step explanation:

What does "at the same time" mean?

If it means that he covered the 240 km in the same time as he convered the 80 km, then this is how you solve it:

80 km in 1.25 hour

240 km in 1.25 hour

Total distance: 80 km + 240 km = 320 km

Total time: 1.25 hour + 1.25 hour = 2.5 hour

average speed = (total distance)/(total time) = 320 km / 2.5 hour = 128 km/h

If it means he covered the 240 km in the same time he covered the 80 km plus the rest, then this is how you solve it:

80 km in 1.25 hour

240 km in 1.25 hour + 45 min = 240 km in 1.25 houir + 0.75 hour = 240 km in 2 hour

Total distance: 80 km + 240 km = 320 km

Total time: 1.25 hour + 2 hour = 3.25 hour

average speed = (total distance)/(total time) = 320 km / 3.25 hour = 98.5 km/h

3 0
2 years ago
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