數學一題!!!中三的,要用substitute去計~

Let Vickey be x years old,teddy be y years old.
x-y=5---------(1)
3/4(x+4)=y+4------(2)
From(1),
x-y=5
5+y=x---------(3)
Sub(3)into (2),
3/4(x+4) =4+y
3/4[(y+5)+4]=y+4
3/4(y+9) =y+4
3/4y+27/4 =y+4
27/4-16/4 =y-3/4y
11/4 =1/4y
y=(11/4)/1/4
y=11years old
Sub y=11into(1)
x-y=5
x-11=5
x=16years old

Vicey is 16years old and teddy is 11years old now.
IF THE ANSWER IS WRONG, DON'T HIT ME~

Let x be the age of Vicky now and y be the age of Teddy now.

x-5=y-------------(1)

3/4(x+4)=y+4------(2)

Substitute (1) into (2).

3/4(x+4)=x-5+4
3/4x+3=x-5+4
4=1/4x
x=16
The age of Vicky is 16,the age of Teddy is 11.