You would use cross multiplication:
X/2,000 = 3/5
Multiply: 2,000*3= 6,000
Divide: 6,000/5
Answer: 1,200 doctors use brand x
A-length
b-width
perimeter of rectangular floor: 2a+2b=204
<span>The length is two times the width: a=2b
</span>2a + 2b = 204
2*2b + 2b = 204
6b = 204|:6
b = 34
a=2b=2*34=68
a=68->length
b=34->width