Linear worded questions! how to solve them :(

[hello_kitty]

ANY HELP WILL BE GREAT!!!

9) A certain number of dollars added to twice as many cents makes $7.14.  Find the number of dollars.
Answer: $7

10) A purse contains x dollars and 6x cents. The total sum amounts to the $5.30.  Find the value of x
Answer: 5

11) If one fifth part of a journey is 3 1/10 km, Find the length of the journey
Answer: 15 1/2 km

12) Olive cycles x kilometres and then walks half as far as she cycled. If she covers 54 kilometres altogether, Find the value of x
Answer: 36

15) The dimensions of a rectangular paddock are as shown in the diagram. 
     Top Length - (3x-100)m,  Width - (x-19)m, and  Bottom Length - (x+6)m 
     Find:
a) The value of x
Answer: 53
b) Length of the paddock
Answer: 59 m
c) the width of the paddock
Answer: 34 m
d) the perimeter of the paddock
Answer: 186 m
e) the area of the paddock
Answer: 2006 m^2

17) A stamp for an ordinary letter costs 40cents, whereas a stamp for a priority letter costs 80cents. If a Post Office employee sells ten times as many 80cents stammps as 40 cent stamps and the total receipts are $126, how many of each type are sold?
Answer: 15 ordinary, 150 priority

20) A carpenter bought ten items. Some cost $40 and the remainder $30.50 each. How many of each were bought if the total cost was $362?
Answer: 6 items at $40, and 4 items at $30.50


THank you so much if anyone can help!


21)

[iNerd]

10)

100x + 6x = 530
106x = 530
therefore x = 5

11)

1/5 = 31/10
5/5 = x

Cross multiply to get 1/5x = 155/50
x = 155/50 divided by 1/5
x = 15.5km

Do the rest later...just make equations!