Question

parallel lines and triangle angle sums
there are two sets of note - cards given that show how to find the values of x and y in the diagram. the set on the left explains the thinking and the set on the right shows the steps. write the thinking and the steps in the correct order.
think cards
subtract 34 from each side.
use the triangle exterior angle theorem to write an equation.
subtract 78 from each side.
write an equation for the angles that form a linear pair.
write cards
y + 78 - 78 = 180 - 78
y = 102
x + 34 - 34 = 112 - 34
x = 78
x + 34 = 112
y + 78 = 180
think
first, you should
second, you should
third, you should
finally, you should
write
step 1
step 2
step 3
step 4

Explanation:

Step1: Use the Triangle Exterior Angle Theorem to write an equation.

$x + 34=112$

Step2: Subtract 34 from each side.

$x + 34-34=112 - 34$
$x = 78$

Step3: Write an equation for the angles that form a linear pair.

$y + 78=180$

Step4: Subtract 78 from each side.

$y+78 - 78=180 - 78$
$y = 102$

Answer:

Step 1: Use the Triangle Exterior Angle Theorem to write an equation.
Step 2: Subtract 34 from each side.
Step 3: Write an equation for the angles that form a linear pair.
Step 4: Subtract 78 from each side.