ok so i will show step by step
3(2x+5)=3(x+15) this is the equation
6x+15=3x+45 distributive the 3 on the outsides of the ()
6x=3x+30 subtract the 15 from both sides
3x=30 now you subtract 3x from both sides
x=10 you will divide 3 from both sides to find x by its self