linear distance - math calc

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I got problem , and don't know how to calculate:

d = s1 * x2 - s2 * x1

we know only value : d and s1 and s2, we don't know x1 and x2

is there any way to know linear value:
1. what is x1-x2 
2. what is x1/x2
3. what is x1*x2
4. what is x1 = l * x2  - where l to should be calculate

please help