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
4 t minus 7 t is equal to 1
C
4 t plus 7 t is equal to 1
D
1 fourth t plus 1 seventh 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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