-15(t^2-5t+4)=0

Solution for -15(t^2-5t+4)=0 equation:

Simplifying
-15(t2 + -5t + 4) = 0

Reorder the terms:
-15(4 + -5t + t2) = 0
(4 * -15 + -5t * -15 + t2 * -15) = 0
(-60 + 75t + -15t2) = 0

Solving
-60 + 75t + -15t2 = 0

Solving for variable 't'.

Factor out the Greatest Common Factor (GCF), '15'.
15(-4 + 5t + -1t2) = 0

Factor a trinomial.
15((-4 + t)(1 + -1t)) = 0

Ignore the factor 15.
Subproblem 1
Set the factor '(-4 + t)' equal to zero and attempt to solve:

Simplifying
-4 + t = 0

Solving
-4 + t = 0

Move all terms containing t to the left, all other terms to the right.

Add '4' to each side of the equation.
-4 + 4 + t = 0 + 4

Combine like terms: -4 + 4 = 0
0 + t = 0 + 4
t = 0 + 4

Combine like terms: 0 + 4 = 4
t = 4

Simplifying
t = 4
Subproblem 2
Set the factor '(1 + -1t)' equal to zero and attempt to solve:

Simplifying
1 + -1t = 0

Solving
1 + -1t = 0

Move all terms containing t to the left, all other terms to the right.

Add '-1' to each side of the equation.
1 + -1 + -1t = 0 + -1

Combine like terms: 1 + -1 = 0
0 + -1t = 0 + -1
-1t = 0 + -1

Combine like terms: 0 + -1 = -1
-1t = -1

Divide each side by '-1'.
t = 1

Simplifying
t = 1
Solution
t = {4, 1}