2. Koda has half as many buttons as Ariya. Koda uses \( \frac{3}{10} \) of her buttons. Ariya uses \( 75 \% \) of her buttons. They then have 96 buttons left altogether. How many buttons does Ariya have at first?

13 If \( \frac{a}{b}=\frac{b}{c}=2 \), then \( \frac{a}{c}=\ldots \ldots \ldots \ldots \) \( \begin{array}{lll}\text { (a) } 2 & \text { (b) } 4 & \text { (c) } 6\end{array} \)

23. Find the equation of a line. Whose intercepts on \( x \) and \( y \) axis are 4 and -6 .

\( 67.04 cm ^ { 2 } = \frac { \sqrt { 26 a } } { 2 } h \)

20 If \( \frac{a}{b}=\frac{c}{d}=\frac{3}{5} \), then \( \frac{a+c}{b+d}=\ldots \ldots \ldots \ldots \) \( \begin{array}{llll}\text { (a) } \frac{5}{3} & \text { (b) } \frac{3}{5} & \text { (c) } \frac{6}{5} & \text { (d) } \frac{5}{6}\end{array} \)

Given: \( \sum_{n=3}^{5} b \cdot 1^{n+1}=54 \) Calculate the value of \( b \)