Question

At Mei's Printing Company LLC there are two kinds of printing presses: Model A which can print 80 books per day and Model B which can print 30 books per day. The company owns 10 total printing presses and this allows them to print 400 books per day. How many of each type of press do they have?

Answer 1

A + B = 10.....A = 10 - B
80A + 30B = 400

80(10 - B) + 30B = 400
800 - 80B + 30B = 400
-80B + 30B = 400 - 800
-50B = - 400
B = -400/-50
B = 8 <=== there are 8 model B printers

A + B = 10
A + 8 = 10
A = 10 - 8
A = 2 <=== there are 2 model A printers