Step by step
The question
Question: find the supplement of 179°.
We call it x.
1 Use the angle fact
Supplementary angles add up to 180°.
Together they make a straight line.
To remember: C comes before S in the alphabet.
90 comes before 180.
So we add the two angles and make it 180: 179 + x = 180.
Careful!
Supplementary means 180, not 90.
90 is for complementary angles.
2 Remove the 179
We want x by itself.
The 179 is in the way.
To remove 179, we take away 179.
We do it on both sides.
Why both sides?
The = sign means both sides are the same amount.
If we change only one side, they are not the same any more.
179 and − 179 make zero.
Cross them out.
180 minus 179 is 1.
So x = 1.
The supplement of 179° is 1°.
3 Check
Let's check: put x = 1 back and add the angles.
They add up to 180°.
So x = 1 is right!
Let's look back.
First: use the angle fact.
Then: remove the 179.
Last: check.