Simon has three numbers. The third number is four more than the first number, and the second number is five more than three times the third number. The sum of the three numbers is sixteen. What is the first number?
+128474 Let the numbers be X, Y and Z in that order
And we have that
X + 4 = Z ⇒ Z - 4 = X (1)
Y = 3Z + 5 (2)
X + Y + Z = 16 (3)
Sub (1) and (2) into (3) and we have that
[Z - 4] + [3Z + 5] + Z = 16 simplify
5Z + 1 =16 subtract 1 from each side
5Z = 15 divide both sides by 5
Z =3
So....the first number, X = Z - 4 = 3 - 4 = -1
