The final price is the cost plus the tax.
Since we know the tax and a percent, we can write this as
T = C(1+r)
T = what Graham paid = $87.45
C = cost before tax
r = tax rate expressed as a decimal = .40
Plugging in what we know
87.45 = C (1+.4)
87.45 = C(1.4)
Divide both sides by 1.4
C = $62.46
In order from left to right its RRRT
R is repeating and T is terminating
Anything raised to exponent 0 equals 1
So
So we get
The new rate will be $15.60
15 * 0.04 = 0.60 + 15 = 15.60
A. is 10! you multiply the scale (2.5) times the length (4)
b. is 6, you divide 15 by 2.5
c. is 5. you do what you did with a but with 2 inches instead of 4
d. is 1.5 you divide 378 by 250
