найдите значение выражения: 5/12а+7при а=4; 4/9b+2/3приb=6; 2/5+1 1/4a при а=2; 2 3/10b+1/2 при b= 5 пожайлуста поогите правильно все напишите

 [tex]\displaystyle \frac{5}{12}a+7; a=4\\\\ \frac{5}{12}*4+7= \frac{5*4}{12}+7= \frac{5}{3}+7=8 \frac{2}{3} [/tex]

[tex]\displaystyle \frac{4}{9}b+ \frac{2}{3}; b=6\\\\ \frac{4}{9}*6+ \frac{2}{3}= \frac{4*2}{3}+ \frac{2}{3}= \frac{10}{3}=3 \frac{1}{3} [/tex]

[tex]\displaystyle \frac{2}{5}+1 \frac{1}{4}a; a=2\\\\ \frac{2}{5}+ \frac{5}{4}*2= \frac{2}{5}+ \frac{5}{2}= \frac{29}{10}=2.9 [/tex]

[tex]\displaystyle 2 \frac{3}{10}b+ \frac{1}{2}; b=5\\\\ \frac{23}{10}*5+ \frac{1}{2}= \frac{23}{2}+ \frac{1}{2}= \frac{24}{2}=12 [/tex]

а) [tex] \frac{5}{12a+7} [/tex] при a = 4
 [tex] \frac{5}{12*4+7}= \frac{5}{55} = \frac{1}{11} [/tex]
б) [tex] \frac{4}{9b} + \frac{2}{3} [/tex] при b = 6
[tex] \frac{4}{9*6} + \frac{2}{3} = \frac{4}{54} + \frac{2}{3} = \frac{4}{54} + \frac{36}{54}= \frac{40}{54} = \frac{20}{27} [/tex]
в) [tex] \frac{2}{5} + 1 \frac{1}{4a} [/tex] при a = 2
[tex] \frac{2}{5} + 1 \frac{1}{4*2} = \frac{2}{5} + \frac{9}{8} = \frac{16}{40} + \frac{45}{40} = \frac{61}{40} = 1 \frac{21}{40} [/tex]
г) [tex]2 \frac{3}{10b} + \frac{1}{2} [/tex] при b = 5
 [tex]2 \frac{3}{10*5} + \frac{1}{2} = \frac{103}{50} + \frac{25}{50} = \frac{128}{50} = 2\frac{14}{25} [/tex]