Given from the number line:
D = -2 and F = 13
So, the distance DF = 13 - (-2) = 13 + 2 = 15
1) find E such that, DE : EF = 2 : 1
so,
so, x : (15 - x) = 2 : 1
x = 30 - 2x
3x = 30
x = 10
So, E = -2 + 10 = 8
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2) E is 4/5 of the distance from F to D
So, the distance from F = 4/5 * 15 = 12
So, E = 13 - 12 = 1
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3) the ratio of DE : EF = 2 : 3
So,
3x = 2 ( 15 - x)
3x = 30 - 2x
5x = 30
x = 30/5 = 6
E = -2 + 6 = 4
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4) E is 1/3 of the distance from D to F
So, the distance DE = 1/3 * 15 = 5
So, E = -2 + 5 = 3
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As a summery:
1) E = 8
2) E = 1
3) E = 4
4) E = 3