Answer:
25X + 25Y = 1700
25X + 100Y = 3200
Step-by-step explanation:
Given that the principal of a high school spent $1700 for X desk and Y chairs at $25 each. Then, the equation will be
25X + 25Y = 1700 ....... (1)
If he had bought half the number of desk in twice the number of chairs he would have spent 1600. That is
25(X/2) + 25(2Y) = 1600
25X/2 + 50Y = 1600
Find the LCM and cross multiply
25X + 100Y = 3200 ........(2)
Your two equations are at the top, in the box is what each variable represents. Below the box is total liters of the 15%, which is going to equal the total liters for 10% plus the total liters for 25%. Make your percentages into decimals. There’s a total of 30 liters so, x+y needs to equal 30. Isolate a variable, I chose y, you can do either or (isolating x would be more math). Y is going to equal 30-x, substitute that for the Y in the second equation, then you need to distribute 0.25 into 30-x. Then it’s simple math, subtract 7.50 from both sides, add like gets, divide both sides by -0.15, making x=20.
It is likely D I am not positive
Answer: 
Step-by-step explanation:
We have given the numbers = 2,0,1,9
We can use addition and subtraction operation to the given numbers such that the answer will be equals to 6.
We can add 2 ,0 and 1 and then subtract from 9 , we will get 6.
So the required expression can be

hence, the required expression can be 