## Prealgebra (7th Edition)

Write a proportion. Size is to size as count is to count. $\frac{20}{55}=\frac{19}{x}$ $\longrightarrow$cross multiply to solve for x $20x=55\times19$ $\longrightarrow$multiply $20x=1045$ $\longrightarrow$multiplication property of equality $20x\div20=1045\div20$ $\longrightarrow$divide $x=52.25$ Pete would not put a part of a tetra in the tank so the answer is 52.