Answer:
r = 2
Explanation:
Actually, there are 2 ways to solve this equation. 
The first one:
5( 3r + 11) = 85
so here,  you have to multiply 5 by ( 3r + 11) and maintain the 85
15r + 55 = 85...   now put the like terms together. In other words, just transpose 55 to the other side. 
15r = 85 -55..... remember that the sign of 55 will change from positive to negative 
15r = 30.... now divide both sides by  15
15r/15 = 30/15
        r = 2
The second method :
5 ( 3r + 11) = 85...... divide both sides by 5
5 (3r + 11) / 5 = 85/5
3r + 11 = 17
3 r = 17 - 11
3r = 6 
r = 2
I hope this helps. If you don't quite get it,  please go through until you get it.  Have a nice day :-)