Answer:
1) F = 100N
2) a = 2 m/s²
3) m = 25 kg
Explanation:
1) F = ma ( F = ?, m = 10 kg, a = 10 m/s² )
 F = 10×10
 F = 100 N
2) F = ma ( F = 20N, m = 10 kg, a = ? )
  20 = 10×a
  10a = 20
  a = 20/10
  a = 2 m/s²
3)F = ma ( F = 100N, m = ?, a = 4 m/s² )
 100 = m×4
 4m = 100
 m = 100/4
 m = 25 kg
Hope that helps! Good luck!
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