Use Pythagoras theorem

Two triangles are similar

(6+3)*12/2 - 6*8 /2 = 30
Answer:
13.6 inches
Step-by-step explanation:
We can use Pythagorean theorem: 
Let c be the diagonal length, a for length, and b for width.
Substitute the values.

c=13.6 inches
Answer: 15 should be the answer hope this helped
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Step-by-step explanation:
1. Cross multiply
35x = 5(11)
35x = 55
Divide both sides by 35
x = 55/35
x = 11/7
2. (x - 2)/x = 3/8
Cross multiply
3x = 8(x - 2)
3x = 8x - 16
Subtract 8x from both sides
-5x = -16
divide both sides by -5
x = -16/-5
x = 16/5 OR 3 1/5
3. (a + 1)/(a - 1) = 5/6
cross multiply
6(a + 1) = 5(a - 1)
distribute
6a + 6 = 5a - 5
subtract 5a from both sides
a + 6 = -5
subtract 6 from both sides
a = -11
4. (1/3)x - 4 = (2/3)x + 6
multiply each term by 3 to clear the fractions
x - 12 = 2x + 18
subtract x from both sides
-12 = x + 18
subtract 18 from both sides
-30 = x
Answer: 8
Step-by-step explanation: numbers are 5 and 3.
5²·3 =75