-10515=21n

Rewrite the equation as 21n=-10515.

21n=-10515

Divide 105 by 15.

21n=-1⋅7

Multiply -1 by 7.

21n=-7

21n=-7

Multiply each term by n and simplify.

Multiply each term in 21n=-7 by n.

21n⋅n=-7⋅n

Cancel the common factor of n.

Cancel the common factor.

21n⋅n=-7⋅n

Rewrite the expression.

21=-7⋅n

21=-7n

21=-7n

Rewrite the equation as -7n=21.

-7n=21

Divide each term by -7 and simplify.

Divide each term in -7n=21 by -7.

-7n-7=21-7

Cancel the common factor of -7.

Cancel the common factor.

-7n-7=21-7

Divide n by 1.

n=21-7

n=21-7

Divide 21 by -7.

n=-3

n=-3

n=-3

Solve for n -105/15=21/n