Respuesta :
Answer:
x = 200
y = 100
Step-by-step explanation:
20x + 30y = 7000 Divide by 10
15x + 35y = 6500 Divide by 5
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It helps if you break down both equations to something simpler. It looks like not always.
(2x + 3y = 700) Multiply by 3
(3x + 7y = 1300) Multiply by 2
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6x + 9y = 2100
6x + 14y =2600 Subtract
-5y = - 500 Divide by -5
-5y/-5 = -500/-5
y = 100
2x + 3y = 700 substitute y = 100
2x+ 3*100 = 700 Combine
2x + 300 = 700 Subtract 300 from both sides.
2x = 700 - 300
2x = 400
x = 400/2
x = 200
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Hockey check
15x + 35y = 6500
15*200 + 35*100 = 6500
3000 + 3500 = 6500 Just as it should.
Answer: 300 seats
Step-by-step explanation:
Easy!
20x + 30y = 7000
15x + 35y = 6500
Simplify by division of a common factor:
5(4x + 6y = 1400)
5(3x + 7x = 1300)
Choose an equation to solve for a variable and use substitution:
4x = 1400 - 6y
x = 350 - 3/2y
3(350 - 3/2y) + 7y = 1300
1050 - 9/2y + 7y = 1300
5/2y = 250
y = 100
Now substitute the solution in both equations to see if it works:
20x + 30(10) = 7000
20x + 3000 = 7000
20x = 4000
2x = 400
x = 200
Now for the other equation:
15x + 35(100) = 6500
15x + 3500 = 6500
15x = 3000
x = 200
Now add x to y, as the total number of seats is equal to x + y.
x + y = total number of seats.
200 + 100 = 300
Therefore, there must be 300 seats in total.