Question

The sum of 3 numbers is -4. The second number decreased by the third is equal to the first. The sum of the first and second numbers is -5. Write the system of equations and find the numbers.

Answer 1

a+b+c= -4
b-c=a
a+b= -5
you can substitute a+b for -5.
-5+c= -4
c=1
you can also substitute a for b-c and c for 1
b-c+b+c= -4
2b= -4
b= -2
then substitute b for -2
a-2= -5
a= -3