Calculate current of resistor with Norton's Theorem
Since you know \$I_{AB} = 8.75A\$ and \$R_n = 2 \Omega\$, calculate \$V_{AB} = 8.75*2 = 17.5V\$. From this, we get \$I_{R4} = V_{AB}/R_4 = 17.5/2.5 = 7A\$. 
If 7A is flowing in \$R_{4}\$ and 5A in \$A_4\$. Rest 2A is coming from \$R_2\$ from KCL.