#### Explanation:

First, we need to find the new cost of the keyboard. 1/4 off is the same as 25% off or a savings of 25% of $48.60. "Percent" or "%" means "out of 100" or "per 100", Therefore 25% can be written as $\frac{25}{100}$. When dealing with percents the word "of" means "times" or "to multiply". Finally, lets call the number we are looking for "n". Putting this altogether we can write this equation and solve for $n$while keeping the equation balanced: n = 25/100 xx$48.60

n = $1215/100 n =$12.15

Because this is the savings we need to subtract this from the old price to obtain the sales price. Therefore:

New price = $48.60 -$12.15 = $36.45 Next we need to calculate the total price Evan will pay including the 6% sales tax. As with above we need to calculate 6% of 36.45. We will call the number we are looking for this time $s$for sales tax. s = 6/100 xx$36.45

s = $218.7/100 s =$2.187 or $2.19 rounded to the nearest penny. The prices Evan will pay for the new keyboard is: $36.45 + $2.19 =$38.64