Assume that you select digits from the set {1,2,4,9}{1,2,4,9} to form a number between 10 and 900. (1) how many such numbers can be formed if digits are not repeated? 12 equation editorequation editor (2) how many such numbers can be formed if digits can be repeated?

1)

          2-digit number                   or               3-digit number                      

4 options x 3 remaining options     +        4 options x 3 options x 2 options

=                      12                               +                          24

=                                                        36

36 different numbers

2)

          2-digit number                   or               3-digit number                      

    4 options x 4 options                +        4 options x 4 options x 4 options

=                      16                             +                          64

=                                                      80

80 different numbers

the inequality is:

250c+180g≥950

step-by-step explanation:

let c denotes the number of days in a week   miyoko worked as a cryptographer.

and g denotes the number of days in a week she works as a geologist.

now we are given that she earns $250 for every day she works as a cryptographer,and earns $180 for every day she works as a geologist.

now miyoko's goal is to earn more than $950 this week.

hence, the inequality could be represented as:

250c+180g≥950