a)
[tex]2a + 1 = 8 \\ 2a = 7 \\ a = \frac{7}{2} = 3 \frac{1}{2} [/tex]
b)
[tex]5a = 3 \frac{3}{4} \\ 5a = \frac{15}{4} | \times 4 \\ 20a = 15 \\ a = \frac{15}{20} = \frac{3}{4} [/tex]
c)
[tex]a \div 6 = 1 \frac{2}{3} \\ \frac{a}{6} = \frac{5}{3} | \times 6 \\ a = 2 \times 5 \\ a = 10[/tex]
d)
[tex]1 \frac{1}{4} + a = 1 \frac{3}{8} \\ \frac{5}{4} + a = \frac{11}{8} | \times 8 \\ 2 \times 5 + 8a = 11 \\ 10 + 8a = 11 \\ 8a = 1 \\ a = \frac{1}{8} [/tex]
e)
[tex]a - 2 \frac{1}{4} = 1 \frac{1}{2} \\ a - \frac{9}{4} = \frac{3}{2} | \times 4 \\ 4a - 9 = 2 \times 3 \\ 4a - 9 = 6 \\ 4 a = 15 \\ a = \frac{15}{4} = 3 \frac{3}{4} [/tex]
f)
[tex]12 \div a = \frac{3}{4} \\ \frac{12}{a} = \frac{3}{4} | \times 4\\ \frac{48}{a} = 3 | \times a \\ 48 = 3a \\ a = \frac{48}{3} = 16[/tex]
Myślę że pomogłem ;)
