3a + b = 54...when b = 9
3a + 9 = 54
3a = 54 - 9
3a = 45
a = 45/3
a = 15 <===
B pretty sure that it’s that
440...marked down by 30% means u pay 70%
70% of 440 = 0.70(440) = 308
308 ..marked down by 10% means u pay 90%
90% of 308 = 0.90(308) = 277.20 <== price after markdowns
