Iknow angle 1 is 76 degrees but i have no idea how to calculate the

Step-by-step explanation:

Angle 2 = 63 degrees because they are alternate interior angles.

Angle 3 is congruent to angle 1 because they are alternate interior angles.

Angle 1 = 76

Angle 1 is 76 because the sum of the interior angles of a triangle equal 180 degrees.

Angle 2 is 63 degrees because the angle that has measurement 63 degrees and angle 2 are alternate interior angles.

Angle 3 is 76 because 1 and 3 are alternate interior angles.

Step-by-step explanation:

Those 2 arrows are big helpers here.

That means they are parallel.

Parallel lines form congruent alternate interior, alternate exterior, and corresponding angles when intersected by a transversal.

Alternate interior angles are the ones that happen inside the parallel lines on opposite sides of the tranversal at the two difference intersections along the transversal.

Correspond angles are the copy and paste angles. That means those are going to be the angles that lay on top of each other if you copy one intersection and paste over the other.

Alternate exterior angles are the ones that happen outside the parallel lines on opposite sides of the transversal at the two different intersections along the transversal.

The measurement of angle 2 is 63 degrees because those angles there are alternate interior.  

The measurement of angle 3 is equal to whatever measurement angle 1 holds because 3 and 1 are alternate interior angles.

(Angle 1)+41+63=180 because the interior angles of a triangle have sum 180 degrees.

(Angle 1)+104=180

Subtract 104 on both sides:

(Angle 1)=180-104

Simplify:

(Angle 1)=76.

So angle 3 is 75.