Layna can paint a 350-square foot room in 4 hours. It takes Bebe 7 hours to paint the same room. Which equation can be used to find the time in hours, t, it takes Layna and Bebe to paint the room together? Rate (Rooms per Hour) Time (Hours) Fraction Completed Layna 1 fourth Bebe 1 seventh
Answer
A
1 fourth t times 1 seventh t is equal to 1
B
1 fourth t plus 1 seventh t is equal to 1
C
4 t minus 7 t is equal to 1
D
4 t plus 7 t is equal to 1
Explanation
Layna paints 1/4 of the room per hour, and Bebe paints 1/7 of the room per hour. Working together, their rates add, so in t hours they complete (1/4)t + (1/7)t of the room. Setting that amount equal to 1 room gives choice B.
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