Question 73144
"Double the sum of a number and 6..." If n is the number then this can be written...{{{2(n+6)}}}
"...is the same as (=) 15 more than triple the same number." This can be written...{{{3n+15}}}.  Put it all together and you get:
{{{2(n+6) = 3n+15}}} Simplify and solve for n.
{{{2n+12 = 3n+15}}} Subtract 2n from both sides.
{{{12 = n+15}}} Subtract 15 from both sides,
{{{-3 = n}}}
The number is -3
Check:
Double the sum of a number and 6.  2(-3+6) = 2(3) = 6
Fifteen more than triple the same number.  3(-3)+15 = -9+15 = 6