Basic Mathematics for College Students

15.HISTORY A 1,700-year-old scroll is 425 years older

than the clay jar in which it was found. How old is

the jar?

Analyze

• The scroll is years old.


• The scroll is years older than the jar.


• How old is the?
  FormLet x the of the jar. Now we look for a key
  phrase in the problem.
  Key phrase:older than
  Translation:
  Now we translate the words of the problem into an
  equation.

is plus

425

Solve

StateThe jar is years old.

Check

This is the age of the scroll.

The result checks.

16. BANKING After a student wrote a $1,500 check to
    pay for a car, he had a balance of $750 in his account.
    How much did he have in the account before he
    wrote the check?
    Analyze
    
    
    • A check was written.
    
    
    • The new balance in the account was.
    
    
    • How much did he have in the account he
      wrote the check?
      FormLet x the account balance he wrote the
      check. Now we look for a key phrase in the problem.
      Key phrase:wrote a check
      Translation:
      Now we translate the words of the problem into an
      equation.
    
    
    
    

minus is

 1,500 

the

new

balance.

the amount

of the

check

The account

balance before

writing the check





 425

x

1,700  425 x

 425 x

 

the age

of the

jar.

425 years

The age

of the

scroll



Solve

StateThe account balance before writing the check

was.

Check

This is the new balance.

The result checks.

17. AIRLINE SEATING An 88-seat passenger plane
    has ten times as many economy seats as first-class
    seats. Find the number of first-class seats and the
    number of economy seats.

Analyze

• There are seats on the plane.


• There are times as many economy as first-class
  seats.


• Find the number of seats and the
  number of seats.
  FormSince the number of economy seats is related to the
  number of first-class seats, we let xthe number of
  seats.
  To represent the number of economy seats, look for a key
  phrase in the problem.
  Key phrase:ten times as many
  Translation:multiply by
  So the number of economy seats.

x  88

Solve

StateThere are first-class seats and economy seats.

CheckThe number of economy seats, 80, is times the

number of first-class seats, 8. Also, if we add the numbers

of seats, we get:

This is the total number of seats.

The results check.



 8

x

11 x



88

 88

x 10 x

is 88.

the number of

economy seats

plus

The number of

first-class seats



 1,500

x

x1,500  750 

1,500 750

684 Chapter 8 An Introduction to Algebra