Question

помогите с номером 4

Answer 1

$\frac5{12}a+\frac34a-\frac12=\frac5{12}a+\frac9{12}a-\frac12=\frac{14}{12}a-\frac12=\frac76a-\frac16\\a=2,1=2\frac1{10}=\frac{21}{10}\\\frac76\cdot\frac{21}{10}-\frac12=\frac72\cdot\frac7{10}-\frac12=\frac{49}{20}-\frac{10}{20}=\frac{39}{20}=1\frac{19}{20}$