Solution:
Let the total field to plow be 100 %
According to the question,
The field plowed before lunch is shown below:
15 acres field = 30%
30 % field = 15 acres
1 % field = 15/30 acres
The field plow after lunch is 70%.
[tex]\begin{gathered} 70\text{ \% of field = }\frac{15}{30}\times70 \\ =35\text{ acres} \end{gathered}[/tex]Final Answer:
Therefore, the field to plow after lunch in order to finish the field is 35 acres.