We can set up a system of equations:
x + y = 12
x - y = 4
Adding these two together:
2x = 16
x = 8
Substituting 8 in the first equation:
8 + y = 12
y = 4
Hope this helps!
Answer:
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against the wind, an airplane travels 3640 km in 7 hours.
with the wind, the same plane travels 6000 km in 6hrs.
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let speed of plane in still air be x mph
speed of wind be y mph.
..
t=d/r
..
against wind speed = x-y mph
with wond speed = x=y mph
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3640/(x-y)=7
3640 = 7x-7y
/7
520=x-y.....................1
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6000/x+y = 6
6000 = 6x+6y
/6
1000=x+y.....................2
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Add (1) & (2)
2x=1520
/2
x=760 mph speed of plane in still air
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plug value of x in 2
1000=760+y
100-760=y
240 = y
240 mph speed of wind
This isn’t easy due to fractions but you just need to find a common denominator, what goes into 9 evenly and also goes into 4 evenly. 36 works and it is the lowest common denominator. What number multiplied by 9 gets you 36? (36/9) 4. So Emma uses 4/36ths of a gallon of gas to get 9/36ths of the way to work. So you take (4/36) or .25 and multiply that by 9 to get...
2.25 trips
Answer:
the correct answer is D...
