Answer:
David=$8.8
Jo=$13.2
Mary=$22
Step-by-step explanation:
2+3+5=10
44/10=4.4
David=4.4x2=$8.8
Jo=4.4x3=$13.2
Mary=4.4x5=$22
8.8+13.2+22=44
2 runners will be needed
1/2 = 2/4
2/4 / 1/4 = 2
2 runners, for 1/2 mile
C. 16x+9=4x
50x / 30/x i think