Answer:
m+n=23
Step-by-step explanation:
the modes m and n have to be data points more than 1 time, but equal
if there are 7 data points, then there are 4 unknown left/2 2 each
(2m-3+m+12+3n+2+m+m+n+n)/7=18
(3m+9+3n+2+m+m+n+n)/7=18
(5m+5n+11)/7=18
(5/7)*m+(5/7)*n+11/7=126/7
(5/7)*m+(5/7)*n=115/7
5m+5n=115
m+n=115/5
m+n=23
