Answer:
22
Step-by-step explanation:
Let the bottom be y for the small triangle
So the total length of the bottom is 2y
We can use ratios to solve
x-1 1y
----- = --------
42 2y
Canceling the y's
x-1 1
----- = --------
42 2
Using cross products
2(x-1) = 42
Divide by 2
x-1 = 21
Add 1 to each side
x-1+1=21+1
x = 22
