Answer:
$30
Step-by-step explanation:
12.50/5=2.50
2.50*12=30
204204 - 16 = 204188
204188 / 4 = 51,047
width = 51,047
length = 51,055
and 
use the second expression to calculate the left-hand side of the first equation:

Add 10 to both sides if this equation to get

and divide both sides by 2

this proves that x = 17, give the two initial equations