If we let Q be the number of quarters and N be number of nickels, this is the formula we would use:
[1] 25Q + 5N = 635 (using cents instead of dollars)
We also know something about Q and N.
[2] Q + N = 51
So multiply both sides of the second equation by 5. The reason we do this is because we're going to need to cancel out one of the variables (either Q or N) to solve for the other one. If we multiply times 5, we'll have 5N in both equations.
5Q + 5N = 255
Now we have two equations, and the second one can be subtracted from the first.
25Q + 5N = 635
-(5Q + 5N) = -255
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20Q = 380
so
Q = 19
There are 19 quarters.
And since there are 51 coins in all, 51-19 = 32 nickels.
The answer is:

Which can be written as: [-8, infinity)
This is the interval from -8 to infinity. So -8 is our left most point on the number line and infinity being our right most. There is no boundary on the right side.
Note how the left side has a square bracket and the right side has a curved parenthesis. This isn't a typo. The square bracket tells the reader "include the endpoint -8 as part of the solution set". The parenthesis tells the reader "do NOT include the endpoint infinity as part of the solution set".
Rule: infinity and negative infinity is always paired with a parenthesis because these aren't numbers. It's impossible to reach infinity, therefore it's impossible to include it in the set of values. If you could include it, then that implies you ran out of numbers.
Answer:
(4x+7)(4x+7)
Step-by-step explanation: