Answer:
The extension is

Step-by-step explanation:
From the question we are told that
The length of the wire on a winter day is

The temperature on the winter day is

The temperature on a summer day is

The the extension of the wire on a summer day is mathematically represented as
![\Delta L = \alpha L_w [T_s - T_w]](https://img.qammunity.org/2021/formulas/physics/college/d0sk1p0ypfvbzcvia69jhcacpj8yq1uixl.png)
Where
is the coefficient of linear expansion of copper with a values

substituting value
![\Delta L = 17 *10^(-6) * 36.0 [34 - [-20]]](https://img.qammunity.org/2021/formulas/physics/college/gnsxqmcehs8y77zmdd8jgz6gija49frwpv.png)
