(a+bi)(2+3i)-i=(-11+5i)(1-i) 2a+3ai+2bi+3bi²-i=-11+11i+5i-5i² 2a+(3a+2b-1)i-3b=-11+16i+5 (2a-3b)+(3a+2b-1)i=-6+16i Therefore; we have the next system of equations: 2a-3b=-6 3a+2b-1=16
Finally, the system of equations is: 2a-3b=-6 3a+2b=17 We can solve this system of equations by reduction method 2(2a-3b=-6) 3(3a+2b=17) ---------------------- 13a=39 ⇒a=39/13=3
Let the age of devaughn be x and Sydney be y. Then,x+y=45 x+5=y y=x+5 here, put y=x+y in x+y=45 then, x+y=45 x+x+5=45 2x=40 x=20 now, y=x+5 y=20+5 y=25