Answer:
The number of computer must Mr. walker sale that week to earn at least $ 1250 is 13 .
Step-by-step explanation:
Given as :
The earning of Mr . walker = $ 600 per week + $ 50 for every computer he sell
Let The number of computer does he must sell to earn $ 1250 for the week = n computers
Now, According to question
$ 600 per week + $ 50 × number of computer he sale = total earning that week
Or, $ 600 per week + $ 50 × number of computer he sale = $ 1250
Or, $ 600 per week + $ 50 × n = $ 1250
or, $ 50 × n = $ 1250 - $ 600
Or, $ 50 × n = $ 650
∴ n = 
I.e n = 13
So, number of computer must he sale to earn $ 1250 = n = 13
Hence The number of computer must Mr. walker sale that week to earn at least $ 1250 is 13 . Answer