This is how you solve this problem:
.10d + .05n = 5.25
(plug in the number of dimes we have)
(21 x .1) + .05n = 5.25
(multiply number of dimes x value of the dime)
2.10 + .05n = 5.25
(subtract 2.10 from both sides)
.05n = 3.15
(divide both sides by .05 to get the number of nickels)
n = 63 nickels
Hope this helps!
Answer:

Step-by-step explanation:
Problems like this require that you recognize that the denominator of the right term is a factor of the denominator of the left term. That is, you're supposed to know how to recognize and factor the difference of two squares.

A function is a set of ordered pairs in which no two different ordered pairs have the same x -coordinate. An equation that produces such a set of ordered pairs defines a function. What is the catch? There can be at most one output for every input.
6 + 8x, where x is a number. You can also write this in standard form as 8x + 6.