Answer :

so we distribute the 2 to the 3m and the +4 so
2*3m=6m 
2*4=8 
6m+8

we then distribute the 3 to the m and the - 5
3*m=3m
3*-5=-15 ((+) times (+) or (-) times (-)=(+), (-) times (+) or (+) times (-)=(-))
3m-15

add 6m+8 and 3m-15
6m+8+3m-15
add like terms (m terms + m terms and number + numbers)
6+3=9 so 
3m+6m=9m
9m-7
Final answer is 9m - 7.
2(3m+4)+3(m-5)
Multiply it out: 6m+8+3m-15
Combine like terms: 6m+3m=9m  8-15= -7
Final answer: 9m-7
Hope this helped!