Drawing scale Q.

40ft/10ft=4

4*3=12

3.5 ft/10=0.35

0.35*3=1.05

6.6ft/10=0.66

0.66*3=1.98

Note  something  that makes  this easier

10ft = 10 * 12 in =  120   in

So

3 in  /10 ft  =  

3 in / 120 in  =    1   / 40    means  that the length on the drawing  is  1 / 40  th   that of  the  actual length

So...now it should be easy

40 ft ( 1/40) = 1 ft  on the  drawing

3.5 ft ( 1/40) =  3.5 /40   = .0875 ft   on the drawing

6.6 (1/40)  =  .165 ft on the  drawing

A scale drawing has a scale of 3 in 10 ft. Find the length on the drawing for each actual length.

* 40 ft. = 480 inches                  *  3.5 ft = 42 inches                   * 6. 6 ft = 79.2 inches

120 / 3 = 480 / x

x = 480 / 40         x = 12      

 y = 42 / 40          y = 1.05

z = 79.2 / 40       z = 1.98