Question 106930
Let's call your number N.
Then 
{{{(3+N)*4=16}}}
To solve the problem, put the knowns on one side and unknown on the other. 
{{{(3+N)*4=16}}}
{{{(3+N)*cross(4)/cross(4)=16/4}}} Divide both sides by 4.
{{{(3+N)=4}}}
{{{cross(3)-cross(3)+N=4-3}}} Subtract 3 from boths sides.
{{{highlight(N=1)}}}
Check your answer.
{{{(3+N)*4=16}}}
{{{(3+1)*4=16}}}
{{{4*4=16}}}
{{{16=16}}}
Your answer led to a true statement. 
It's a good solution. 
Your number is 1.