Step-by-step explanation:
12/3.48= cost of 1 book
cost of 20 books = 12/3.48×20 =68.95
The answer is 5. Hope that helps :)
Answer:
Step-by-step explanation:
The goal to solving any equation is to have x = {something}. That means we need to get the x out from underneath that radical. It's a square root, so we can "undo" it by squaring. Square both sides because this is an equation. Squaring both sides gives you

Get everything on one side of the equals sign and set the quadratic equal to 0:

Throw this into the quadratic formula to get that the solutions are x = 5 and -8. We need to see if only one works, both work, or neither work in the original equation.
Does
?
and

and 5 = 5. So 5 works. Let's try -8 now:
and
so

-8 = 8? No it doesn't. So only 5 works. Your choice is the third one down.
Answer:

multiply all terms in the top equation by 2
multiply all terms in the second equation by -7. it would then add the two equations together to cancel out the variable x
You will then have two equations in terms of y
solve for y and either equation then substitute that value for y into the other equation then solve for x