Chapter 5, Systems of Equations and Inequalities - Section 5.1 - Systems of Linear Equations in Two Variations - 5.1 Exercises - Page 448: 68

$2.5$ pounds of the Kenyan, and $0.5$ pound of the Sri Lankan.

If he uses $x$ pounds of the Kenyan, he uses $3-x$ of the Sri Lankan. Then our equation is: $3.5x+(3-x)5.6=11.55\\3.5x+16.8-5.6x=11.55\\2.1x=5.25\\x=2.5$ Thus, he used $2.5$ pounds of the Kenyan, and $3-2.5=0.5$ pound of the Sri Lankan.