Answer:
substituting x=5y into 2x-3y=7, Answer: y = 1 x = 5
Step-by-step explanation:
2(5y)-3y=7
10y-3y=7
7y=7
y=1
substitute y=1 into x=5y
x=5(1)
x=5
Answer:
120
Step-by-step explanation:
Let's say you put them on the shelf one by one, from left to right.
You can pick 1 of the 5 for the first position.
5
Now you have 4 books left. You pick one out of those 4 for the second position.
5 * 4
There are 3 choices left for the 3rd position.
5 * 4 * 3
2 left for the 4th position.
5 * 4 * 3 * 2
Finally, there is one book left for the 5th position.
5 * 4 * 3 * 2 * 1
Now we multiply:
5 * 4 * 3 * 2 * 1 = 120
