\[Стр.\ 68.\]
\[\boxed{\mathbf{3.}}\]
\[\boxed{\mathbf{4.}}\]
\[\boxed{\mathbf{5.}}\]
\[\textbf{а)}\ 7,25 - 0,99 = 6,26\]
\[\textbf{б)}\ 9,34 + 4,98 = 14,32\]
\[\textbf{в)}\ 146,2 + 99,9 = 246,1\]
\[\textbf{г)}\ 49,9 - 47,81 = 2,09\]
\[\textbf{д)}\ 9,99 + 0,01 = 10\]
\[\textbf{е)}\ 11 - 6,8 = 4,2\]
\[\textbf{ж)}\ 0,13 + 0,87 = 1\]
\[\textbf{з)}\ 51,84 - 0,84 = 51\]
\[\boxed{\mathbf{6.}}\]
\[\textbf{а)}\ 3,7a + 4,3a = 8a\]
\[\textbf{б)}\ 16,5b - 7,5b = 9b\]
\[\textbf{в)}\ 18x - 0,7x = 17,3x\]
\[\textbf{г)}\ 13,9y + 7,2y = 21,1y\]
\[\textbf{д)}\ 0,4a + 0,5a + 0,1a = a\]
\[\textbf{е)}\ 8,6b - 3,2b - 5,4b = 0\]
\[\textbf{ж)}\ 2x - 1,5x - 0,3x = 0,2x\]
\[\textbf{з)}\ 5y + 0,7x + 1,8x = 5y + 2,5x\ \]