Question

1. write an equation and solve for x. equation: x =

Explanation:

Step1: Use angle - sum property of triangle

The sum of interior angles of a triangle is 180°. So, the equation is $(x + 55)+56 + 78=180$.

Step2: Simplify the left - hand side

$x+(55 + 56+78)=x + 189$. So the equation becomes $x + 189=180$.

Step3: Solve for x

Subtract 189 from both sides: $x=180 - 189=-9$.

Answer:

Equation: $(x + 55)+56 + 78=180$
$x=-9$