## Prealgebra (7th Edition)

Write a proportion. Mph decrease is to mph decrease as time is to time. $\frac{3}{x}=\frac{5}{8}$ $\longrightarrow$cross multiply to solve for x $5x=3\times8$ $\longrightarrow$multiply $5x=24$ $\longrightarrow$multiplication property of equality $5x\div5=24\div5$ $\longrightarrow$divide $x=4.8$ New speed is $45-4.8=40.2$