Show the following 2 equations are formed from this data and solve simultaneously to find E and r

an unknown battery (unknown emf (E) and internal resistance(r)) is connected to a 4 ohm resistor which causes a current of 2 amps to flow in the circuit. when the battery is connected to a 2 ohm resistor a current of 3 amps flows.

E-2r=8
E-3r=6

this formula may help l=E/(R+r)
where l is amps, E is emf, R is resistance in ohms and r is internal resistance

3r + 6 = 2r + 8
r = 2 ohms
E = 4 + 8 = 12 volts