Answer:
? = 130
Step-by-step explanation:
I'm letting ? be x
Since the triangles are similar, larger outer and smaller inner, then the ratios of corresponding sides are equal.
If x is the length of side of larger then x - 70 is corresponding length of smaller.
Then
[tex]\frac{x}{x-70}[/tex] = [tex]\frac{78}{36}[/tex] ( cross- multiply )
78(x - 70) = 36x ← distribute left side
78x - 5460 = 36x ( subtract 36x from both sides )
42x - 5460 = 0 ( add 5460 to both sides )
42x = 5460 ( divide both sides by 42 )
x = 130
