We have the following table
hour pay
1 12
2 24
3 36
4 ?
It seems that for each hour we work, we end up earning $12. Then, we know that if we work 3 hours we earn 36. So, if we work one more hour (4) we should add 12 to what we earn for working 3 hours. That is
So we aren 48 for working 4 hours.