90 + 20x + 10x = 180
30x = 90
x = 3
Answer:
11.4
Step-by-step explanation:
So we know that Triangle ACB is similar to Triangle EFD.
This means that their sides are proportional to each other.
We want to find x or side AB. To do so, we can set up a proportion.
The proportional side to AB is ED. Let's also use BC since we know its value. The proportional side to BC is DF. Thus:

Substitute x for AB, 3.8 for Ed, 15 for BC, and 5 for DF. Thus:

Reduce the right:

Cross multiply:

So, the value of x is 11.4
And we're done!
Answer: " b = 3 ⅕ ; or, write as: 3.2 .
_____________________________________
Given: "A = (1/2) * b * h " ;
↔ A = (b * h) / 2
2A = (b*h) ;
2A/ h = b ;
↔ b = (2A) / h ;
Given A = 48 ; and h = 30 ; Plug in these values; and solve for "b" ;
→ b = (2*48) / 30 ;
= 96/30 ;
= (96÷6) / (30÷6) ;
→ b = 16/5 ; = 3 <span>⅕ ; or, write as: 3.2 .
_______________________________</span>