x = regular gas
y = premium gas
Boricua: The cost of 14 gallons of regular gasoline and 10 gallons of premium gasoline is $46.68.
equation1:
14*x+10*y = 46.68
Boricua: Premium costs $0.30 more per gallon than regular
equation2:
y = x + 0.30
[input]solve( 14*x+10*y=46.68, y=x + 0.30 )[/input]
14*x+10*y = 46.68 with y = x + 0.30 is
14*x+10*(x + 0.30) = 46.68
14*x+10x + 3.0 = 46.68 | -3
14*x+10x = 43.68
24x = 43.68 | /24
x = 43.68/24 =
1.82 (regular gas)
y = x + 0.3 =
2.12 (premium gas)
price for premium in germany:
[input]1.69eur/l in $/gal[/input]
+3146 
