His old apartment cost 750*$2=$<<750*2=1500>>1500 a month
His new apartment cost $2800/2=$<<2800/2=1400>>1400 a month
So he saves $1500-$1400=$<<1500-1400=100>>100 a month
That means he saves $100*12=$<<100*12=1200>>1200 a year
#### 1200