Let x represent the number of liters of 50% acid Theresa puts into the mix. The the number of liters of 30% acid will be (420-x). The total amount of acid in the final solution will be ...
0.50x + 0.30(420-x) = 0.45(420)
0.20x + 126 = 189 . . . . . . . . . . . . . . . simplify
0.20x = 63 . . . . . . . . . . . . . . . . . . . . . subtract 126
x = 63/0.20 = 315 . . . . . . . . . . . . . . . liters of 50% solution
(420-x) = 420-315 = 105 . . . . . . . . . liters of 30% solution
Theresa should mix ...
105 liters of 30% solution
315 liters of 50% solution
In rolling one die, there are 6 possible outcomes because each die has 4 faces. The number of outcomes when rolling n dice is equal to 6^n. By this, the number of outcomes when 2 dice are rolled is 36, 216 for 3 dice, and so on.
E = 352.50 euro × 1 pound / 1.41 euro = 250.00 pounds
J = 39856 yen × 1 pound / 188 yen = 212.00 pounds
a) Japan is cheaper
b) 250 - 212 = 38 pounds cheaper