Answer:
Step-by-step explanation:
We are to show that 
<u>Proof:</u>
From trigonometry identity;


From trigonometry, 2sinAcosA = Sin2A

Also note that sin(B-C) = sinBcosC - cosBsinC
sin420cos140 - cos420sin140 = sin(420-140)
The resulting equation becomes;

= 
The area of the pentagon is 140
To find the amount he spent on bags of mulch you must take the cost of the shovel away from the total, giving the equation:
46.16-14.75=3.49x
To covert this to whole numbers, multiply by 100
4616-1475=349x
3141=349x
x=9