Answer:
Xavier's age = 23
Yifei's age = 27
Step-by-step explanation:
Represent Yifei's age with Y and Xavier's age with X;
Given that the sum of their ages is 124;
X + Y = 124
Also, given that Yifei is 4 years older
Y = X + 4
Required
Find their age when they got married
From the parameters above, we've been able to form a simultaneous equation
[tex]X + Y = 124[/tex]
[tex]Y = X + 4[/tex]
Substitute X + 4 for Y in the first equation
[tex]X + X + 4 = 124[/tex]
[tex]2X + 4=124[/tex]
Subtract 4 from both sides
[tex]2X + 4 - 4 = 124 - 4[/tex]
[tex]2X = 120[/tex]
Divide both sides by 2
[tex]\frac{2X}{2} = \frac{120}{2}[/tex]
[tex]X = 60[/tex]
Substitute 60 for X in the second equation
[tex]Y = X + 4[/tex] becomes
[tex]Y = 60 +4[/tex]
[tex]Y = 64[/tex]
To get their ages when they got married; we simply subtract 37 from their current ages
Xavier's age = 60 - 37
Xavier's age = 23
Yifei's age = 64 - 37
Yifei's age = 27
