3x + y - 1 = 30

3x - y = 23

3x + y = 31 {added 1 to each side of first equation}

3x - y = 23 {second equation stays the same}

--------------

6x = 54 {added the two equations}

x = 9 {divided each side by 6}

3x - y = 23 {second equation}

3(9) - y = 23 {substituted 9, in for x, into second equation}

27 - y = 23 {multiplied}

-y = -4 {subtracted 27 from each side}

y = 4 {divided each side by -1}

**x = 9 and y = 4***- Algebra House*
**
**