a factory produces 1 defective bulb out of 10 bulbs a yr. if it produces 870 bulbs a yr, how many defective bulbs are produced?  Choose the correct answer
A) 84 B) 85 C) 86 D) 87 E) 88
10 out of 1 is defective   20 out of 2 is defective   100 out of 10 is defective   and so on   800 out of 80 is defective   70 out of 7 is defective    80+7= 
<gadget id="calculator"> 80+7</gadget>
<output>87</output>
87   ANSWER:87
<result>D</result>
a factory produces 1 defective bulb out of 10 bulbs a yr. if it produces 870 bulbs a yr, how many defective bulbs are produced?