Answer:
The father did more.
13/28 needs to be mowed which is 0.4643 of the lawn needs to be mowed.
Explanation:
The best way to compare the two is to change them to decimals. That will at least answer who mowed the most.
Father: 2/7 = 0.2857
Son: 1/4 = 0.25
Since the father mowed 2/7 of the lawn, he mowed the most.
You can use the decimals to get the second part.
Together they did 0.25 + 0.2857 = 0.5357
The amount of the lawn left is 1 - 0.5357 = 0.4643
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If you must have this in fractions then
1/4 + 2/7 = 7/28 + 2*4/28 = 7/28 + 8/28 = 15/28
15/28 = 0.5357 which is just what we got above.
Amount left to do = 1- 15/28 = 13/28
13/28 = 0.4643 which is what we got about.