The sum of three numbers 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 1

just write the facts in symbols.

x+y+z = 23
x = 2y-7
z = 1+(x+y)

Now just solve for x.

Answer 2

2nd number ---- x
1st number = 2x-7
3rd = x + 2x-7 + 1 = 3x - 6

x + 2x-7 + 3x - 6 = 23

carry on

Answer 3

A change machine contains nickels,dimes, and quarters. There are 75 coins in the machine, and the value of the coins is $7.25. There are 5 times as many nickels as dimes. How many quarters are in the machine?