V=k*q/d" voltage of any charge on the any point " V_A=k*q_1/sqrt 74 " potential of charge of -2C on the point(7,5)" V_B=k*q_1/sqrt 85" potential of charge of -2C on the point(9,-2)" V_(AB)=V_B-V_A V_(AB)=k*q(1/sqrt 85-1/sqrt 74) V_(AB)=k*q(sqrt 74-sqrt 85)/sqrt (74*85) W=q*V_(AB) "energy required for charge of 4C to move from(7,5) to (9,-2)" W=4*k*q(sqrt 74-sqrt 85)/sqrt (74*85) W=4*(-2)(sqrt 74-sqrt 85)/sqrt (74*85)* W=-8*(8,602-9,219)/(79,31) W=0,062 J