Answer:
![c=18.90-2.1r](https://img.qammunity.org/2020/formulas/mathematics/middle-school/p1h400vepbj46unfc4qlvyfmo11bjtbi8u.png)
Explanation:
The complete question is
A chef bought $17.01 worth of ribs and chicken. Ribs cost 1.89 per pound and chicken costs 0.90 per pound. The equation 0.90 +1.89r = 17.01 represents the relationship between the quantities in this situation.
Show that each of the following equations is equivalent to 0.9c + 1.89r = 17.01.
Then, explain when it might be helpful to write the equation in these forms.
a. c=18.9-2.1r. b. r= -10÷2c+9
we have that
The linear equation in standard form is
![0.90c+1.89r=17.01](https://img.qammunity.org/2020/formulas/mathematics/middle-school/wu0vsp1xwvyrd4qi7yf0e0fgnryfdr7ji6.png)
where
c is the pounds of chicken
r is the pounds of ribs
step 1
Solve the equation for c
That means ----> isolate the variable c
Subtract 1.89r both sides
![0.90c=17.01-1.89r](https://img.qammunity.org/2020/formulas/mathematics/middle-school/wjemeemf3h6taywopqvsod0zjw373skvnt.png)
Divide by 0.90 both sides
![c=(17.01-1.89r)/0.90](https://img.qammunity.org/2020/formulas/mathematics/middle-school/1e5aavwb0fdn3xfbgmboy3qooloykzyk45.png)
Simplify
![c=18.90-2.1r](https://img.qammunity.org/2020/formulas/mathematics/middle-school/p1h400vepbj46unfc4qlvyfmo11bjtbi8u.png)
step 2
Solve the equation for r
That means ----> isolate the variable r
Subtract 0.90c both sides
![1.89r=17.01-0.90c](https://img.qammunity.org/2020/formulas/mathematics/middle-school/2d4wzea5csfj4mfhovkl3rugk3p2g91ws8.png)
Divide by 1.89 both sides
![r=(17.01-0.90c)/1.89](https://img.qammunity.org/2020/formulas/mathematics/middle-school/4niuhlssi26fudiex7ofmok1jh7jxloh6k.png)
Simplify
![r=9-0.48c](https://img.qammunity.org/2020/formulas/mathematics/middle-school/4h2sb7pbatig3edwuvkhl6rv7kriqwhdei.png)
therefore
The equation
is equivalent
The equation is helpful, because if I want to know the number of pounds of chicken, I just need to substitute the number of pounds of ribs in the equation to get the result.