I need help with geometry

It 12

Step-by-step explanation:

This is because the scale factor between the triangles is 1.75, so I divide 21 by 1.75 and got 12

Hope this helped

We first have to find 2 pairs of sides that proportional.

35/20=42/24=7/4

and 21/b should be 7/4 as well because if we want the triangles to be similar the sides should be in proportion.

21/b=7/4

84=7b

b=12

Done!

Hope this helped, any questions about this just ask in the comments and I will answer.

she will sew have sewn five dresses   and be 1/3 done with the sixth one in an hour.

step-by-step explanation:

3/4 of an hour=45 mins

lucy makes 1 dress per 11.25 minutes

45 mins+11.25 mins=56.25 mins

60 mins- 56.25 mins=3.75 mins

3.75 mins is 1/3 of of 11.25 mins

therefore she the other 1/3 would be part of the hour and she will have sewn 5 dresses and begun the sixth.

contact me if you have any questions you are welcome.