91Ó°ÊÓ

A mathematical model is an equation that describes the relationship between two quantities. For example, the lifeexpectancy at birth of Americans can be approximated by the equation $$y=0.212 x-347$$ where \(x\) is a year between 1943 and 2005 and \(y\) is age in years. 1985

Evaluate each expression for \(x=6, y=-4,\) and \(a=3\) $$ (5 x-2 y)(-2 a) $$

Translate each phrase into a mathematical expression. Use \(x\) as the variable. Combine like terms when possible. A number multiplied by \(5,\) subtracted from the sum of 14 and eight times the number

Evaluate each expression for \(x=6, y=-4,\) and \(a=3\) $$ (-5+x)(-3+y)(3-a) $$

Evaluate each expression for \(x=6, y=-4,\) and \(a=3\) $$ \frac{x y+8 a}{x-y} $$

Write a numerical expression for each phrase and simplify. Twice the product of \(-1\) and \(6,\) subtracted from \(-4\)

Write a numerical expression for each phrase and simplify. See Examples 8 and \(9 .\) The difference between 7 and \(-14\)

Solve each problem. Paul Beaulieu's favorite recipe for barbecue sauce calls for \(2 \frac{1}{3}\) cups of tomato sauce. The recipe makes enough barbecue sauce to serve seven people. How much tomato sauce is needed for one serving?

Solve each problem. Kyla Williams needs \(2 \frac{1}{4}\) yd of fabric to cover a chair. How many chairs can she cover Twith \(23 \frac{2}{3}\) yd of fabric?

Write a numerical expression for each phrase and simplify. The sum of \(-18\) and \(-6,\) divided by the product of 2 and \(-4\)