SOLUTION: The sum of three number is 23 the first number is equal to twice the second number minus 7 the third number is equal to one more than the sum of the first and second numbers what i

Question 386731: The sum of three number is 23 the first number is equal to twice the second number minus 7 the third number is equal to one more than the sum of the first and second numbers what is the first number

Answer by gwendolyn(128) (Show Source): You can put this solution on YOUR website!
Let's assign variables to the three numbers.
let x=the first number
let y=the second number
let z=the third number
When all the numbers are added together, their total is 23. This can be expressed in an equation:
x+y+z=23
x is 2 times y minus 7, which can be said as:
x=2y-7
Finally, the question states that z is 1 plus x plus y. So:
z=1+x+y
We can substitute the values of x and y that we have from our second and third equations into our first equation:
x+y+z=23
2y-7+y+1+x+y=23
Next, we can simplify the equation:
2y-7+y+1+x+y=23
4y-6+x=23
4y+x=29
Then, we can substitute the value of x into the equation again:
4y+x=29
4y+2y-7=29
6y=36
Finally, we divide both sides by 6 to isolate the variable and find y's value:
y=6
We can then substitute y's value into the equation for x, which the question asked us to find.
x=2y-7

x=12-7
x=5
Therefore, the first number is 5.
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