26. \( \sqrt{15 \cdot 3-\frac{126}{14}} \) 27. \( \frac{16}{9}+\frac{1}{6} \cdot \frac{9}{4} \)

To solve the first expression, you can simplify the terms inside the square root. First, calculate \( \frac{126}{14} \), which equals 9. Now, substituting that back into the expression gives you \( 15 \cdot 3 - 9 \), or \( 45 - 9 = 36 \). Therefore, \( \sqrt{36} = 6 \). For the second expression, start with \( \frac{16}{9} + \frac{1}{6} \cdot \frac{9}{4} \). Multiply the fractions \( \frac{1}{6} \) and \( \frac{9}{4} \), which equals \( \frac{9}{24} \) or \( \frac{3}{8} \). Now convert \( \frac{16}{9} \) to a common denominator with \( \frac{3}{8} \), which gives \( \frac{128}{72} + \frac{27}{72} = \frac{155}{72} \) when added together.