17 + 5shirts = 42
5shirts = 42-17 = 25
1shirt = 25/5 = 5
A shirt costs £5.
3*5 + 1hat = 17
15 + 1hat = 17
1hat = 2
A hat costs £2
I believe your answer should be 105x squared-1475x+70
sorry i'm not really sure how to put the little two above the first x but my answer is mathematically correct.