Answer:
173.8 pounds of carbon dioxide are emitted into the atmosphere when the truck travels 139 miles.
Explanation:
Each gallon is said to emitt 20 pounds of carbon dioxide.
So we have to solve two rules of three to answer this problem.
The first one is to know how many gallons were used.
Each gallon lasts 16 miles. How many gallons are needed for 139 miles?
1 gallon - 16 miles
x gallons - 139 miles.
![16x = 139](https://img.qammunity.org/2020/formulas/mathematics/college/o6l75fuctn71l3uok7x1hemg338n7mjfbc.png)
![x = 8.6875](https://img.qammunity.org/2020/formulas/mathematics/college/io4hpxjdneutuyyxzhfak9sz7b9y1enp94.png)
8.6875 gallons are used.
Now we find how many pounds of carbon dioxide are emitted.
1 gallon - 20 pounds
8.6875 gallons - x pounds
![x = 20*8.6875](https://img.qammunity.org/2020/formulas/mathematics/college/o8o94nm4wiowtr4z2d9glljcgak4bl5uso.png)
![x = 173.8](https://img.qammunity.org/2020/formulas/mathematics/college/ysga16p60mov52kjno4ebhw6pebjy1k1wn.png)
173.8 pounds of carbon dioxide are emitted into the atmosphere when the truck travels 139 miles.