-t=9(t-10)

Apply the distributive property.

-t=9t+9⋅-10

Multiply 9 by -10.

-t=9t-90

-t=9t-90

Subtract 9t from both sides of the equation.

-t-9t=-90

Subtract 9t from -t.

-10t=-90

-10t=-90

Divide each term in -10t=-90 by -10.

-10t-10=-90-10

Cancel the common factor of -10.

Cancel the common factor.

-10t-10=-90-10

Divide t by 1.

t=-90-10

t=-90-10

Divide -90 by -10.

t=9

t=9

Solve for t -t=9(t-10)