Answer:
[tex]the \: cost \: for \: 70 \: yards \: of \: material \: is : \\ \: \$210.[/tex]
Step-by-step explanation:
[tex]let \: the \: cost \: of \: material \: be \to \: c_{m} \\ let \: the \: amount \: of \: material \: be \to \: a_{m} \\ then \: the \: expression \: is: \\ c_{m} \: \alpha \:a_{m} \\ c_{m} \: = k a_{m} \\ if \: c_{m} = 42 \: and \:a_{m} = 14 \\ then \: \to \\ k = \frac{c_{m} }{a_{m}} = \frac{42}{14} \\ k = 3 \to \: this \: is \: the \: variation \: constant. \\ when \: a_{m} = 70 : \: then \to \\ c_{m} = k a_{m} = 3 \times 70 \\ \boxed{ c_{m} = \: 210}[/tex]
♨Rage♨
