Answer:
Here's how I would do it.
Explanation:
If two triangles are similar, corresponding sides are in the same ratio.
We know the measures of b and a, so we can calculate the ratio b/a.
d and b are in the same ratio, so
![\begin{array}{rcl}(d)/(c)& = & (b)/(a)\\d & = & c * (b)/(a)\\\end{array}](https://img.qammunity.org/2020/formulas/mathematics/middle-school/kblbipeakxer4ylfemiy4tpwbodaalw9mq.png)
We know the measures of c, b, and a, so we can calculate the value of d.