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.

£56

step-by-step explanation:

u divide 24 by 3 and u get 8 so if u do 8 time 7 or 8+8+8+8+8+8+8 u get 56 and 56 divided by 7 is 8.