Obviously, in these kind of examples, the solution must demonstrate that both sides are equal. The strategy is to discover which number n will make the fraction equivalent.
Start with the numerators, those numbers at the top of the fractions, -2 & 10. Is there a factor of 10 that will leave us with -2?
So -5 is the factor 10 that leaves us with -2. Now we divide 6 by that same factor:
Another way to do this is cross-multiplication. Multiply n by 10 & multiply -2 by 6. These two products must be equal:
Use basic algebra to solve for n: