\[\begin{array}{l}
a)\frac{8}{{36}} + \frac{4}{9} = \frac{{8:4}}{{36:4}} + \frac{4}{9} = \frac{2}{9} + \frac{4}{9} = \frac{{2 + 4}}{9} = \frac{6}{9} = \frac{{6:3}}{{9:3}} = \frac{2}{3}\\
b)\frac{{18}}{{15}} + \frac{4}{3} = \frac{{18}}{{15}} + \frac{{4 \times 5}}{{3 \times 5}} = \frac{{18}}{{15}} + \frac{{20}}{{15}} = \frac{{18 + 20}}{{15}} = \frac{{38}}{{15}}\\
c)\frac{2}{3} + \frac{6}{9} = \frac{2}{3} + \frac{{6:3}}{{9:3}} = \frac{2}{3} + \frac{2}{3} = \frac{{2 + 2}}{3} = \frac{4}{3}\\
d)\frac{6}{{12}} + \frac{3}{2} = \frac{{6:6}}{{12:6}} + \frac{3}{2} = \frac{1}{2} + \frac{3}{2} = \frac{{1 + 3}}{2} = \frac{4}{2} = 2
\end{array}\]

M

a)836+49=8:436:4+49=29+49=2+49=69=6:39:3=23b)1815+43=1815+4×53×5=1815+2015=18+2015=3815c)23+69=23+6:39:3=23+23=2+23=43d)612+32=6:612:6+32=12+32=1+32=42=2