Ответ:

  1. \((3+a)\cdot5=15+5a\).
  2. \((8+b)\cdot2=16+2b\).
  3. \((x+4)\cdot11=11x+44\).
  4. \((c-3)\cdot7=7c-21\).
  5. \((5-d)\cdot3=15-3d\).
  6. \(2\cdot(12+b)=24+2b\).
  7. \(9\cdot(3-p)=27-9p\).
  8. \(5\cdot(8+4t)=40+20t\).
  9. \(10\cdot(2q-3)=20q-30\).
  10. \(31\cdot(2+n)=62+31n\).
  11. \(16\cdot(a+b)=16a+16b\).
  12. \(23\cdot(x-y)=23x-23y\).
  13. \(12\cdot(7-2a)=84-24a\).
  14. \((3-k)\cdot13=39-13k\).
  15. \(25\cdot(m+4)=25m+100\).