00:01
Okay, so we are given in this problem that triangle a, b, c is congruent to triangle d .e .f.
00:07
We are also given that the length of a .b.
00:11
Is equal to 2x minus 10, and that the length of d .e.
00:15
Is equal to x plus 20.
00:17
So since corresponding parts of congruent triangles are also congruent, length ab, the length of segment a .b, is equivalent or congruent.
00:31
Equivalent to the length of de.
00:37
Those two segments are congruent to each other.
00:40
And so i'm going to say since a .b, the length of a .b is equal to d .e.
00:48
I can substitute in their expressions.
00:52
So 2x minus 10 is equal to x plus 20.
00:58
Now i have variable on either side, but they are the same variable.
01:04
Just different coefficients, and i have number terms on either side.
01:10
So since i have 2x on this side and only 1x on this side, i'm going to begin by consolidating my xs by subtracting x on this side.
01:20
And when i subtract x, i'm not getting rid of the variable.
01:24
I'm subtracting 1x from each side.
01:27
This is 1x minus 1x, which is 0x.
01:29
X.
01:31
On this side, i have 2x minus 1x, which remains 1x minus 10 is equal to 0x or 0 plus 20.
01:43
So 20.
01:45
Next, i will, now that i've chosen aside for my variable, i'm going to get the numbers onto the other side.
01:52
So this term, i need to be the opposite.
01:56
If i subtract 10, then i need to add 10 back, and that will undo this calculation, which means that i'll be left with 1x minus 10 plus 10, that's zero, so 1x...