Answer:
17
Step-by-step explanation:
I won't answer them all for you (don't want to cheat - need to learn something).
But for the first one given:
<span>-2x-9y=-25
-4x-9y=-23
you set up either x or y (which ever one you want to eliminate) so that one of them cancels.
So this one is easy - you just have to multiply an entire row by negative (doesn't matter which one) - so that the y's will be + and -
Since they're both 9 and they're subracting NOW - you can eliminate the y value. Now add/subtract the x's. So it'd be -2 or 2 depending on how you eliminated y. Then add the number outside of the = sign. Now just solve for x. After that plug in whatever you got for x into both of the rows. Then find the y value.
Hopefully this wasn't confusing -- reply if it is and I will try to simplify. I can give you contact if you need help with the rest
Good luck!</span>
Answer:

Step-by-step explanation:
At the start of the day there are g pounds of gravel in the quarry.
Then it says that there were 300 pounds added to the mound, so at this point the pounds of gravel in the mound are now g+300.
Then two orders of 700 pounds are sold and removed from the mound. That means they removed 700 pounds from the mound 2 times. Therefore at this point the pounds of gravel in the mound are now g+300-700-700.
Then it says that at this point, the amount of pounds in the mound are 1500. Hence we get

To solve for g we just add 700 two times to both sides of the equation, and subtract 300 from both sides of the equation, getting:

And so 