I would solve the first equation for x and then sub that value into x in the second equation. That's the easiest way. x - 2y = 3 solved for x is x = 2y+3. Now sub that in for x in the second equation: 5(2y+3)+3y=2 and 10y + 15 + 3y = 2. 13y = -13, and y = -1. Now sub that y value into either equation to solve for x: x = 2(-1) + 3 gives us an x value of x = 1. Therefore, your solution to this system is (1, -1), first choice above.
Because you have to go in the order of PEMDAS, parenthesis, exponents, multiplication, division, addition, and subtraction. From what you are saying, 'why you must simplify 3 to the second power first' it seems that you have no parenthesis, so you move onto what is next, which is exponents, in this case, 3 to the power of two.
You must multiply 2.5 by 7 to get the answer which is 17.5 pounds
1 pound of bread contains
cups of cinnamon.
<h3><u>
Solution:</u></h3>
Given that , In
pound of a banana bread, there is
cup of cinnamon
<em><u>To find:</u></em>
Amount of cinnamon per pound in bread
Let "n" be the cinnamon per pound present in bread
pound of banana bread ⇒
cup of cinnamon
Then, 1 pound of bread ⇒ n cups of cinnamon
Now, let us use criss cross method (i.e. multiplying the diagonal ordered terms and equating them)

Hence, 1 pound of bread contains
cups of cinnamon.