Chapter ISG, Problem 6.4.8P

To determine

To write a system of equations

Answer to Problem 6.4.8P

  $x+y=125$ and $5x+10y=990$

Explanation of Solution

Given information:

Total number of bills=125

Total value of bills=$990

Calculation:

Let number of 5 dollar bill be $x$ and 10 dollar bills be $y$ .

According to question,

  $x+y=125$  -(1)

And,

  $5x+10y=990$   -(2)

To determine

To solve the system of equations

Answer to Problem 6.4.8P

The number of 5 dollar bills are:52

And, number of 10 dollar bills are:73

Explanation of Solution

Given information:

Total number of bills=125

Total value of bills=$990

Calculation:

Theequations are:

  $x+y=125$   -(1)

  $5x+10y=990$   -(2)

Taking (1)

  $x=125-y$   -(3)

Put x in (2)

  $5(125-y)+10y=990$

Solving,

  $625-5y+10y=990$

So,

  $5y=365$

Dividing equation by 5,

  $y=73$

Put value of y in (3)

  $x=125-73$

So,

  $x=52$

Hence, number of 5-dollar bills are 52 and number of 10 dollar bills are 73