1.
[tex]\frac{2c}{8} = 1\frac{1}{2}\\\\\frac{2c}{8} = \frac{3}{2}\\\\2c\cdot2 = 3\cdot8 \ \ |:4\\\\\boxed{c = 12}[/tex]
2.
[tex]\frac{3d}{2} = 2\frac{1}{4}\\\\\frac{3d}{2} = \frac{9}{4}\\\\3d\cdot4 = 9\cdot2\\\\12d = 18 \ \ |:12\\\\d = \frac{18}{12} = \frac{3}{2}\\\\\boxed{d = 1\frac{1}{2}}[/tex]
3.
[tex]3\frac{3}{4}\cdot 2y = 30\\\\\frac{15}{4}\cdot2y = 30\\\\\frac{15}{2}y = 30 \ \ |\cdot\frac{2}{15}\\\\y = \frac{60}{15}\\\\\boxed{y = 4}[/tex]
4.
[tex]3a + 1\frac{3}{4} = 2\frac{1}{5}\\\\3a = 2\frac{1}{5}-1\frac{3}{4}\\\\3a = \frac{11}{5}-\frac{7}{4}\\\\3a = \frac{44}{20}-\frac{35}{20}\\\\3a = \frac{9}{20} \ \ |:3\\\\\boxed{a = \frac{3}{20}}[/tex]
