Вычислите, используя законы сложения:
а) $\frac{17}{30} + \frac{28}{30} = \frac{15 + 2 + 28}{30} = ...$;
б) $\frac{29}{40} + \frac{37}{40}$;
в) $\frac{58}{61} + \frac{45}{61}$;
г) $\frac{257}{300} + \frac{199}{300}$;
д) $\frac{379}{401} + \frac{127}{401}$.
$\frac{17}{30} + \frac{28}{30} = \frac{15 + 2 + 28}{30} = \frac{15 + (2 + 28)}{30} = \frac{15 + 30}{30} = \frac{45}{30} = \frac{3 * 15}{2 * 15} = \frac{3}{2}$
$\frac{29}{40} + \frac{37}{40} = \frac{26 + 3 + 37}{40} = \frac{26 + (3 + 37)}{40} = \frac{26 + 40}{40} = \frac{66}{40} = \frac{33 * 2}{20 * 2} = \frac{33}{20}$
$\frac{58}{61} + \frac{45}{61} = \frac{53 + 5 + 45}{61} = \frac{53 + (5 + 45)}{61} = \frac{53 + 50}{61} = \frac{103}{61}$
$\frac{257}{300} + \frac{199}{300} = \frac{256 + 1 + 199}{300} = \frac{256 + (1 + 199)}{300} = \frac{256 + 200}{300} = \frac{456}{300} = \frac{38 * 12}{25 * 12} = \frac{38}{25}$
$\frac{379}{401} + \frac{127}{401} = \frac{376 + 3 + 127}{401} = \frac{376 + (3 + 127)}{401} = \frac{376 + 130}{401} = \frac{506}{401}$
Пожауйста, оцените решение