4.
[tex]F = m\cdot g \ \ /:g\\\\m = \frac{F}{g}[/tex]
[tex]a)\\F = 850 \ N\\g = 3,7\frac{m}{s^{2}}\\\\m = \frac{F}{g}\\\\m = \frac{850 \ N}{3,7\frac{m}{s^{2}}}=\frac{850 \ kg\cdot\frac{m}{s^{2}}}{3,7\frac{m}{s^{2}}} \approx229,7 \ kg[/tex]
[tex]b)\\F = 5 \ 400 \ N\\g =9,81\frac{m}{s^{2}}\\\\m = \frac{F}{g}\\\\m = \frac{5400 \ N}{9,81\frac{m}{s^{2}}} = \frac{5400 \ kg\cdot\frac{m}{s^{2}}}{9,81\frac{m}{s^{2}}}\approx550,5 \ kg[/tex]
[tex]c)\\F = 276 \ N\\g = 1,62\frac{m}{s^{2}}\\\\m = \frac{F}{g}\\\\m = \frac{276 \ N}{1,62\frac{m}{s^{2}}} = \frac{276 \ kg\cdot\frac{m}{s^{2}}}{1,62\frac{m}{s^{2}}}\approx170,4 \ kg[/tex]