At a carnival a food stall sold bags of cotton candy for $5 each and bags of popcorn for $7 each. A total of 140 bags were sold
1 answer:
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9514 1404 393
Answer:
(x, y) ≈ (1.1642, 3.3930) and (3.4358, -0.39297)
Step-by-step explanation:
Solve the first equation for y, then substitute into the second.
5x +4/y = 7
4/y = 7 -5x
4/(7 -5x) = y
Then the second equation becomes ...
4x +x/(4/(7 -5x)) = 5
4x +x(7 -5x)/4 = 5
16x +7x -5x^2 = 20 . . . . . multiply by 4
5x^2 -23x +20 = 0 . . . . . put in standard form
We can use the quadratic formula to solve this.
x = (23±√((-23)² -4(5)(20)))/(2(5)) = (23±√129)/10
x = 2.3 ±√1.29 ≈ {1.1642, 3.4358}
y = 4/(7 -5x) = {3.3930, -0.39297}
Solutions are (x, y) ≈ (1.1642, 3.3930) and (3.4358, -0.39297).
The perimeter would be 
and the area would be 
.