A contractor bought 10.8 ft2 of sheet metal. She has used 2.1 ft2 so far and has $261 worth of sheet metal remaining. The equation 10.8x−2.1x=261 represents how much sheet metal is remaining and the cost of the remaining amount. How much does sheet metal cost per square foot?

the solution of the equation is 2.23 ⇒ answer b

step-by-step explanation:

* lets revise the meaning of exponential function

- the form of the exponential function is y = ab^x, where a ≠ 0, b > 0 ,  

  b ≠ 1, and x is any real number

- it has a constant base b

- it has a variable exponent x

- to solve an exponential equation, take the log or ln of both sides,  

  and solve for the variable

* lets solve the problem

∵

- the base is 7 and the exponent is x

- insert ㏑ in both sides

∴

- use the rule

∴ x ㏑(7) = ㏑(77)

- to find x divide both sides by ㏑(7)

∴

* the solution of the equation is 2.23 to the nearest 2 decimal places

one fourth of 9% = 2.25%

gavin is correct in saying : the equivalent quarterly interest rate would be

2.25%.

the answer is z7+8/5