Chapter ISG, Problem 2.7.4P

a.

To determine

To write an equation

Answer to Problem 2.7.4P

  $y=(0.75d-7.5)\times 8.52-62.2$

Explanation of Solution

Given information:

  $e=0.75d-7.5$

  $y=6.2d-62$

  $y=8.5e-62.2$

Calculation:

Using 3^rd formula,

Solving for y

  $8.52e=62.2+y$

So,

  $e=\frac{62.2+y}{8.52}$

(1)

Now,

  $e=0.75d-7.5$

Substituting value of e,

  $\frac{62.2+y}{8.52}=0.75d-7.5$

Solving,

  $62.2+y=(0.75d-7.5)\times 8.52$

Now,

  $y=(0.75d-7.5)\times 8.52-62.2$

Hence, this is the equation.

b.

To determine

To find solution

Answer to Problem 2.7.4P

  $d=337.36$

It would be better to convert Yuan to dollar

Explanation of Solution

Giveninformation:

  $e=0.75d-7.5$

  $y=6.2d-62$

  $y=8.5e-62.2$

Calculation:

The given equation is

  $y=6.2d-62$

And another equation is

  $y=(0.75d-7.5)\times 8.52-62.2$

Solving them,

  $(0.75d-7.5)\times 8.52-62.2=6.2d-62$

So,

  $6.39d-63.9-62.2=6.2d-62$

Now,

  $0.19d=64.1$

So,

  $d=337.36$

It would be better to convert Yuan to dollar as it is direct formula