Help I have a math question?

Question

: An apple contains 4.5 g of fiber and 19 g of sugar. A banana contains 3 g of fiber and 14 g
of sugar. If a barrel of fruit contains 0.279 kg of fiber and 1.218 kg of sugar, how many

Puzzling · Answer

Let's just work in grams
--> 0.279 kg = 279 g 
--> 1.218 kg = 1218 g

Let a be the number of apples
Let b be the number of bananas

Amount of fiber in the barrel:
4.5a + 3b = 279

Amount of sugar in the barrel:
19a + 14b = 1218

That's two equations and two unknowns so you can solve from there. I'm going use elimination, so let's get the same coefficient for the 'b' term:

Multiply the first equation by 14:
14(4.5a + 3b) = 14(279)
63a + 42b = 3906

Multiply the second equation by 3:
3(19a + 14b) = 3(1218)
57a + 42b = 3654

We can subtract these two equations and eliminate b:
63a + 42b = 3906
57a + 42b = 3654
------------------------
6a .......... = 252
a = 252/6
a = 42

Then use any equation and solve for b:
4.5a + 3b = 279
4.5(42) + 3b = 279
189 + 3b = 279
3b = 90
b = 90/3
b = 30

Answer:
42 apples and 30 bananas

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Help I have a math question?

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