Question

Help Me PLZ!!!!!!!! need help

The following numerically ordered sequence of number's has a mean of 17 and a median of 18.
7,a,12,15,17,b,20,22,24,25
Given this information, the values of a & b must be

Answer 1

b must be 19 because
(17+19)/2=the median of 18
a must be 9 because
(7+9+12+15+17+19+20+22+24+25)/10=
170/10=the mean of 17