Answer:
Half of a number is 15
Step-by-step explanation:
First of all, add commas between each option so it's easier to read I had a hard time figuring out what the options were because of this.
An equation is a statement that the values of two mathematical expressions are equal. An expression is a collection of symbols that jointly express a quantity. This means there has to be an equal sign when the phrases are put into numerical form.
Twice as much as a number: 2X
12 less than a number: X - 12
Half of a number is 15: X/2 = 15
The difference of 20 and a number: 20 - X
As you can see, only one of these phrases is an equation by definition, and that is X/2 = 15, or half of a number is 15. That's because it's the only one that values two expressions as equal.
Answer:
Step-by-step explanation:
Answer: x = 7 and y = -2
Step-by-step explanation:
2x +3y = 8 ----------------(1)
x-y = 9 ----------------------(2)
multiply (2) by 2
2x-2y = 18--------------------(3)
subtract (2) from (3)
-5y = 10
Divide bothside by -5
y = -2
Similarly, multiply (2) by 3
3x-3y = 27-----------------------(4)
add (1) and (4) together
5x = 35
Divide bothside by 5
x= 7
Therefore, x =7 and y= -2
Answer:
A dime is worth 2 nickels.
let no of dimes be x
let no of nickles be y
so as per the data mentioned in the question , x=2*y-10
total amount = $2.75
so total amount should comprise of nickels and dimes
x*dimes + y*nickels = $2.75
x*( 2 nickels)+ y *nickels = $2.75
=> nickles( 2x+y) = $ 2.75
but 20 nickels = 1 dollar
nickles(2x+y) = 2.75*20 nickels
cancelling nickles on both sides
2x+y = 55
already we know that x= 2y-10
so 2(2y-10) +y= 55
4y-20+y=55
5y -20 =55
add 20 on both sides
5y-20+20=55+20
5y=75
divide with 5 on both sides
5y/5 =75/5
y= 15
so x= 2y-10
x= 2*15-10
x= 30-10
x= 20
so # of dimes =20
# of nickels =15
