You should first find out what lines are what,
Like for example, If you had 5 - 10 - 15 as the Y Lines and the bar was between 5 and 10 then your best bet would be to estimate what the middle of 5 and 10 is which would be 7 or 8.

From there we can see that because x equals both to a and b, it must be that a = b.
Answer:
45
Step-by-step explanation:
n/15=30
therefore n=450
hence n/10 = 45
Cos 18 = x/25
x = 25 cos 18
x = 25(0.9510) = 23.775 ~ 23.78 cm
Answer:
y=1+1/3x
Step-by-step explanation: