Answer:
500 lb
Step-by-step explanation:
Let x lb be the weight of seawater needed to get 17.5 lb of salt.
Now,
x lb - 100%
17.5 lb - 3.5%
Write a proportion:
[tex]\dfrac{x}{17.5}=\dfrac{100}{3.5}[/tex]
Cross multiply:
[tex]x\cdot 3.5=100\cdot 17.5\\ \\x=\dfrac{100\cdot 17.5}{3.5}=500\ lb[/tex]
