Question 257123
Let A be the first number, B be the second.
1.{{{B=A+4}}}
2.{{{A+B=56}}}
Substitute eq. 1 into eq. 2 and solve for A. 
2.{{{A+B=56}}}
{{{A+(A+4)=56}}}
{{{2A=52}}}
{{{A=26}}}
Then use eq.1, 
{{{B=A+4}}}
{{{B=30}}}