Respuesta :

5 times the quantity 2 m + 6 n minus 3 n
=
5 *2 m + 6 n- 3 n
=10m + 6n -3n

5 times the quantity 2 m = 10m
6 n minus 3 n = 6n-3n

so......

10m+6n-3n

Answer : B. 
10m+6n-3n

Hoped I helped! :)