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
Answer:
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Step-by-step explanation:
918x3=2754 the answer is 2757 wecome
1. Observe that the f(t) is change by 4 per time t => there's a acceleration of 4 => f''(t) = 4; Take the derivative of it we can get a velocity function. f'(t) = 4t + c. Since the velocity from 100 to 80 is -20 (average), this means at t = 0, f'(0) = -22 => f'(t) = 4t - 22; Take the derivative again to get the position function: f(t) = 2t^2 - 22t + d, here d = 100 should be trivial. So, the function that models the relationship is f(t) = 2t^2 - 22t + 100.
2. By the compound interest formula:
A = P (1 + r/n)^(nt) , since it's yearly, so n = 1;
results A(t) = 100 (1+0.12)^t.
3. The average rate of change is basically finding the slope, m = y1 - y2 / x1 - x2.
