First bring all terms in 'a' to the left side of the formula by subtracting ac from both sides
ab - ac - cd = ac - ac
ab - ac - cd = 0
now add cd to both sides
ab - ac -cd + cd = cd
ab - ac = cd
now factor the left side by taking out the 'a'
a(b-c) = cd
now divide both sides by (b-c)
a = cd / (b-c)
done
I don’t know I need the points for my homework though, deepest apologies
Since the photo booth charges a $500 fee for two hours at the party and an additional 50 dollars per hour, we have:
50x+500=C
Where x is the hours stayed and C is the total cost. Since Cindy doesn't want to spend more than 700 dollars, we have:

So she spent an additional 4 hours on the rental.
Answer:
Step-by-step explanation:
If the center of the circle is at the origin, the general formula for the circle is
x^2 + y^2 = r^2.
Since r = 2 units in this particular problem, the equation of the circle is:
x^2 + y^2 = 2^2, or x^2 + y^2 = 4