I'll take this challenge since I'm not feeling lazy for once.... x would represent Gavin and y would represent Seiji.
a. [tex]x+y=425, x-y=25 [/tex]
b. I will solve your system using substitution.
[tex]x+y-425, x-y=25[/tex]
Step 1: Solve [tex]x+y=425[/tex] for x
[tex]x+y+-y=425+-y [/tex] (add -y for both sides)
[tex]x=-y+425[/tex]
Step 2: substitute [tex]-y+425[/tex] for x in [tex]x+b=25[/tex]
[tex]x+y=25[/tex]
[tex]-y+425-y=25[/tex]
[tex]-2y+425=25 [/tex] (simplify both sides of the equation)
[tex]-2y+425+-425=25+-425 [/tex] (add -425 to both sides)
[tex]-2y=-400[/tex]
[tex] \frac{-2y}{-2} = \frac{-400}{-2} [/tex]
y=200
step 3: substitute 200 for y in [tex]x=-y+425[/tex]
[tex]x=-y+425[/tex]
[tex]x=-200+425
[/tex]
[tex]x=225[/tex]
[tex]x=225, y= 200[/tex]
c. Already answered with the picture that is attached.
d. Gavin earned 225 dollars while Seiji earned 200 dollars.
