1:2 equals 0.8. What's the ratio?

The answer is 2
One in five is one in two, that is, one in five multiplied by two equals two in five
Eight is four fifths
Four fifths is two fifths more than x
The solution is x = 2

2 / (1-x) = 2.5 why do I always equal 0.25

2/(1-x)=2.5
2.5(1-x)=2
2.5-2.5x=2
2.5x=2.5-2
2.5x=0.5
x=0.2
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Using - 3, - 5, 0, 3, 4, it's 24

[(-3)-(-5)+0]×3×4=24

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