Algebra Demystified 2nd Ed

244 algebra De mystif ieD

number is eight more than this, so x + 8 represents the other number.

Their sum is 70, giving us x + (x + 8) = 70.

xx

x

x

x

x

++=

+=

−−

=

=

=

() 870

2870

88

262

62

2

31

The numbers are 31 and x + 8 = 31 + 8 = 39.

The sum of two numbers is 63. One of the numbers is twice the other.

Find the numbers.

Let x = first number, and 2x = other number.

Their sum is 63, so x + 2 x = 63.

xx

x

x

x

+=

=

=

=

263

363

63

3

21

The numbers are 21 and 2x = 2(21) = 42.

PRACTICE

1. The sum of two numbers is 85. One number is 15 more than the other.
   What are the two numbers?


2. The sum of two numbers is 48. One number is three times the other.
   What are the numbers?

PRACTICE

1. The sum of two numbers is 85. One number is 15 more than the other.