A painting crew painted 80 houses. They painted the first y houses at a rate of x houses per week. Then more painters arrived and everyone worked together to paint the remaining houses at a rate of 3.25x houses per week. How many weeks did it take to paint all 80 houses, in terms of x and y?  Options
A) (320 - y)/(5x) B) (y +220)/(5x) C) 5(80 - y)/(4x) D) (y + 400)/(4x) E) (4y + 320)/(5x)
Ans (y +220)/(5x)   Plug some numbers   Let y = 40 houses and x = 20   then they painted 20 houses per week   as painters were added to the group , the rate of the group increased to 3.25 x =&gt; 3.25 * 20= 
<gadget id="calculator">3.25 * 20</gadget>
<output>65</output>
65 houses per week   total time they took= (40/20) + (40/65) = 2.6 weeks   Putting the values of x and y in equation (y +220)/(5x)   (y +220)/(5x) = (40+220)/5*20 = 260/100= 
<gadget id="calculator">260/100</gadget>
<output>13/5 = around 2.6</output>
2.6
<result>B</result>
A painting crew painted 80 houses. They painted the first y houses at a rate of x houses per week. Then more painters arrived and everyone worked together to paint the remaining houses at a rate of 3.25x houses per week. How many weeks did it take to paint all 80 houses, in terms of x and y?