**5. The sum of three natural numbers is 15. The second number is 1 more than the first number. The sum of the first and third numbers is equal to twice the second number. Find all three numbers.**

**Answer:**

x+y+z=15

y=x+1

x+z=2y

Rearrange the 1st equation

(x+z)+y=15

Substitute

2y+y=15

3y=15

y=5

Substitute into 2nd equation

5=x+1

x=4

Substitute into 1st equation

4+5+z=15

z=6

4,5,6