Answer:
b = 6
Step-by-step explanation:

I would say the answer is 9. BUT again I'm not sure what your asking!
Answer:
∠TUY = 120°
Step-by-step explanation:
There are two rules you can apply here:
1) The sum of the angles inside a triangle is 180°. This means that ∠SUT = 180° - 70° - 50 ° = 60°
2) A vector coming out of a line two angles between itself and the line, and they add up to 180° as well. This means that ∠TUY = 180° - ∠SUT. So ∠TUY = 180° - 60° = 120°
So the missing angle one hundred and twenty degrees.
Bookshelf =7boards each
Lumber=4 boards each
He wants to make 5 bookshelves total
5x7=35
So he needs 35 boards
And each lumber makes 4 boards
So what number times 4 is equal to or more than 35?
9times 4 is 36
So he needs 9 pieces of lumber to make 5 bookshelves.
Good luck with your work! Brainliest would be appreciated :)