1. ABC Megamart sold 4 sacks more than half its sacks of rice on the first day of a week. It sold 3 sacks fewer than half ofthe remaining sacks of rice on the second day. ABC Megamart ordered another 30 sacks of rice on the third day. It had a total stock of 50 sacks then. How many sacks of rice did ABC Megamart have at first?
2. ABC Telco sold 20 more than half its cell phone inventory in January. It sold 15 more than half remaining number of cell phones in February. It had 75 cell phones left March before any purchase was made. How many cell phones did ABC Telco carry at first?
Let the original amount of sacks of rice be $s$.
After the first day, we have that $s-(1/2s+4)=1/2s-4$ sacks remaining.
The second day, they had $(1/2s-4)-(1/2(1/2s-4)-3)=1/4s+1$ sacks remaining.
The third day, they had $s/4+1+30=s/4+31$ sacks remaining, because they ordered 30 sacks.
So, we have $s/4+31=50$.
Let the original amount of cell phones be $s$.
After the first month, we have that $s-(1/2s+20)=1/2s-20$ cell phones remaining.
After the second month, we have that $(1/2s-20)-(1/2(1/2s-20)+15)=1/4s-25$ cell phones remaining.
We have now that $1/4s-25=75$.