The sum of three consecutive numbers is –15. what is the largest number?

Consecutive numbers are numbers that follow one right after the other. One example is the set {6, 7, 8}. We don't know the three consecutive numbers so let's define...

x = first number
x+1 = second number
x+2 = third number

where x, x+1, and x+2 are consecutive numbers



"The sum of three consecutive numbers is -15" meaning that
x+(x+1)+(x+2) = -15

Let's solve for x
x+(x+1)+(x+2) = -15
x+x+1+x+2 = -15
3x+3 = -15
3x+3-3 = -15-3
3x = -18
3x/3 = -18/3
x = -6

So this means

first number = x = -6
second number = x+1 = -6+1 = -5
third number = x+2 = 6+2 = -4

The list of consecutive values is {-6, -5, -4}

They add up to (-6) + (-5) + (-4) = -11+(-4) = -15
which confirms we have the right values



In short, the final answer is -4