I'm not sure which formula to use because it's not indicated, but I'll just solve for x in both equations.
3x + 7 = 19
First I would subtract 7 on both sides:
3x = 12
Then I would divide 3 on both sides:
x = 4
x - 1 = 5
I would just add 1 on both sides:
x = 6
Hope I helped :)
