Answer:
He bough 1.25 lbs of shrimp and 3.75 lbs of potato.
Explanation:
Since the stew is composed of shrimps and potatoes, then the sum of the weighs of these ingredients must be equal to the weigh of the stew, so we have:
![shrimp + potato = 5](https://img.qammunity.org/2021/formulas/mathematics/high-school/tfjh3e5q6sd1tj3x2tn8p3a4yam9jsxyi6.png)
We also know that he bought three times more potatoes than shrimps, therefore:
![potato = 3*shrimp](https://img.qammunity.org/2021/formulas/mathematics/high-school/yjzvlgxivwuv7wgiq23zmhm9uqm0ai6snk.png)
Using the second equation on the first one, we have:
![shrimp + 3*shrimp = 5\\4*shrimp = 5\\shrimp = (5)/(4) = 1.25](https://img.qammunity.org/2021/formulas/mathematics/high-school/4wg9vd40dn550ghjkacpyxlhhzj7xhwka2.png)
![potato = 3*shrimp = 3*1.25 = 3.75](https://img.qammunity.org/2021/formulas/mathematics/high-school/e8nxi6dc3oyg1or6crndw0mtpl5b6xan4m.png)
He bough 1.25 lbs of shrimp and 3.75 lbs of potato.