Solve {l}{a_{1}+a_{3}=10}{a_{3}+a_{5}=40}{a=a_{1}}{text{Solvefor}btext{where}}{b=a}

$$\left. \begin{array} { l } { a_{1} + a_{3} = 10 }\\ { a_{3} + a_{5} = 40 }\\ { a = a_{1} }\\ { \text{Solve for } b \text{ where} } \\ { b = a } \end{array} \right.$$

Solve for a_1, a_3, a_5, a, b

$$a_{1}=b$$

$$a_{3}=10-b$$

$$a_{5}=b+30$$

$$a=b$$