To solve this question, you first need to identify w. To do so, you do:
tan(39) = w/15.19
tan(39) x 15.19 = w
w=12.87m (2.dp)
After this, you solve for theta like so:
tan(θ) = 12.87/8.5 --> i got 8.5 from substracting 7.4 from 15.9
θ= tan^-1(12.87/8.5)
θ=56°33' and thats ur answer!