Answer:
x+2y=12-------(1)
x-2y=3---------(2)
Adding equations 1 and 2
we get
2x=18
x=9
Equation 1
9+2y=15
2y=15-9
2y=6
y=3
The solution of the given system is x=9, y=3
Step-by-step explanation
6. If 55% of the selling price is markup, the remainder (45%) is the cost. Gaitan can pay up to 45% of 489.50 = $220.28.
7. If 52% of the selling price is markup, the remainder (48%) is the cost. 48% of the selling price is $38.87.
... 0.48 × selling price = cost
... selling price = cost/0.48 = $38.87/0.48 = $80.98
8. If 40% of the selling price is markup, the remainder (60%) is the cost, $12.95.
... 0.60 × selling price = $12.95
... selling price = $12.95/0.60 = $21.58
9. If 35% of the selling price is markup, the remainder (65%) is the cost.
... 0.65 × $24.00/dz = $15.60/dz
10. If 60% of the selling price is markup, the remainder (40%) is the cost. Veronica can pay up to 40% of $600.00 = $240 for the jacket.
Answer: 84
<u>Step-by-step explanation:</u>
Set up a proportion as follows: 

Cross multiply: 12x = 7 × 144
Divide by 12: x = 7 × 12
Simplify: x = 84