Sachindh wrote:cost of 3 fox jeans = 45
cost of 2 pony jeans = 36
let x be discount on fox jeans and y be on pony jeans
therefore
45*x/100 + 36*y/100 = 9
15x + 12y=300 ----- eq i
also x+y = 22 ----- eq ii
solving both equation, we get x=12, y=10.
Good job on the algebra.
If we could actually see all the choices, it would also be incredibly quick to solve this via backsolving, i.e. working backwards from the answers.
Using the correct answer as an example:
if Pony is 10%, then fox is 12%.
2 pairs of pony @ $18 each = $36. 10% savings = $3.60
3 pairs of fox @ $15 each = $45. 12% savings = $4.50 + $0.90 = $5.40
Total savings = $9, which matches the question stem. Correct answer!
If we had gotten savings of less than $9, we would have looked for a smaller answer, since the pony jeans make up the smaller part of the purchase, so increasing the discount on fox would increase the overall discount. If we had gotten savings greater than $9, we'd have looked for a bigger answer. By starting with either (B) or (D), we'd guarantee only having to check 2 choices and have a 40% chance of getting it right on the first shot.
Moral of the story: if the algebra jumps out at you, it's probably fastest to do the algebra; if the algebra doesn't jump out at you, look for an alternative method like backsolving, picking numbers or strategic guessing.
