Answer:

Step-by-step explanation:
see the attached figure with letters to better understand the problem
step 1
In the right triangle ACD
Find the length side AC
Applying the Pythagorean Theorem

substitute the given values



simplify

step 2
In the right triangle ACD
Find the cosine of angle CAD

substitute the given values

----> equation A
step 3
In the right triangle ABC
Find the cosine of angle BAC

substitute the given values
----> equation B
step 4
Find the value of x
In this problem
----> is the same angle
so
equate equation A and equation B
solve for x
Multiply in cross


step 5
Find the length of BC
In the right triangle BCD
Applying the Pythagorean Theorem

substitute the given values



simplify

Answer:
a) y = 9.95(x-3) + 20.00
b) Cost of 5 software packages = $39.90
Step-by-step explanation:
Given that:
Cost of 3 software at sale = $20
Cost of regular = $9.95
Let,
x be the number of software purchased.
We will subtract 3 from x because they cost $20.
y be the total cost.
y = 9.95(x-3)+ 20.00
Putting x=5 in expression
y = 9.95(5-3) + 20.00
y = 2(9.95) + 20.00
y = 19.90 + 20.00
y = $39.90
Hence,
a) y = 9.95(x-3) + 20.00
b) Cost of 5 software packages = $39.90