___-1=10-3
x-1=10-3
x-1=7
x=8
therefore the blank is 8
Answer:

Step-by-step explanation:
Area of a circle with radius
: 
Circumference of a sector with radius
: 
Area of sector with angle
:
.
Arc length of sector with angle
: 
Using these equations, we get the following information:
Area of circle: 
Circumference of a circle: 
Area of sector: 
Arc length of sector: 
75(x-2) where x represents the amount originally paid
Not sure what x' means but
seems to be the reverse distributive property
normally written as
a(b+c)=ab+ac
we can see the similarity
a(x'+y)=ax+ay
distributive property