9514 1404 393
Answer:
total: 2.85 hours = 2 17/20 hours
Explanation:
Strategy: convert all fractions to decimals, determine weeding and mowing times, and add the three times to find the total.
3/4 = 0.75
1/5 = 0.2
Solution:
raking time: 0.75 hours
weeding time: 0.75 +0.2 = 0.95 hours
mowing time: 0.95 +0.2 = 1.15 hours
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Total time: 0.75 +0.95 +1.15 = 2.85 hours = 2 17/20 hours
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Additional comment
You may recognize that 0.95 is the middle of three equally-spaced values. Then the total will be 3×0.95 = 2.85 hours.