RICAS Grades 6-8 Ratios and Proportional Relationships. Practice it free.

Use a conversion factor with centimeters in the numerator so millimeters cancel: $80 \text{ mm} \times \dfrac{1 \text{ cm}}{10 \text{ mm}} = 8 \text{ cm}$.

Three gallons of water is $3 \times 16 = 48$ cups. With a $7$ to $56$ ratio, $\dfrac{7}{56} = \dfrac{x}{48}$, so $56x = 336$ and $x = 6$ cups of concentrate.

$\dfrac{4}{5} = 0.8 = 80\%$.

Discount: $\dfrac{40}{100} \times \text{\char36}30 = \text{\char36}12\textsf{.}$ Sale price: $\text{\char36}30 - \text{\char36}12 = \text{\char36}18\textsf{.}$

$\dfrac{82}{100} = 0.82 = 82\%\textsf{.}$

Convert $45\%$ to a decimal and multiply: $0.45 \times 360 = 162$ chairs.

$25\% = 0.25\textsf{.}$ Then $0.25 \times 100 = 25\textsf{.}$

Discount: $\frac{25}{100} \times \text{\char36}200 = \text{\char36}50$. Sale: $\text{\char36}200 - \text{\char36}50 = \text{\char36}150$.