Do you want us to do all seven? I don't think so.
17. s for Sonia, m for Sam, n for Nigel
s = 13.2 + 1.4 m
n = -10 + 2.5 m
n = 12 + s
First and third,
n = 12 + (13.2 + 1.4 m)
Second and that one,
-10 + 2.5m = 25.2 + 1.4m
1.1m = 35.2
m = 35.2/1.1
m = 32
Answer: 32 kg
18.
f - # of $500 tickets, t - $300 tickets, w - $200 tickets
t = 2f
w = -60 + t
500f + 300t + 200w = 48000
f = t/2
500(t/2) + 300t + 200(-60 + t) = 48000
750t = 60000
t = 80
w = -60 + t = 20
Answer: 20
19.
c + b = 171
c/9 = b/9 -5
c = b - 45
Adding,
2c + b = b + 126
c = 63
Answer: 63
Three's my limit.