Answer:
Solution given:
model A printers [a] prints=80books per day
model B printers [b] prints=55books per day
total no of printers =9
no of model A printers be x
and
no of model B printers be [9-x]
According to the question;
ax+(9-x)b=670 books
substituting value of a and b; we get
80x+(9-x)55=670
80x-55x+495=670
25x=670-495=175
x==7
So;
no of model A printers =x=<u>7</u>
no of model B printers =9-x=9-7=<u>2</u>
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