Sagot :
The solution is very long. So, just bear with it.
Let x be the present age of Abel, and y be the present age of Angela.
x
y
(Abel and Angela's age 3 years ago)
x-3
y-3
(Angela's age was 1 year more than 3 times Abel's)
3(x-3) + 1 = y-3 -------------------- (First Equation)
(4 years from now, Angela's age will be 2 years more than 2 times the age of Abel)
2(x+4) + 2 = y+4
(Reduce)
3(x-3) + 1 = y-3
3x-9 + 1 = y - 3
3x-9+1+3 = y
3x-5 = y ---------- (reduced first equation)
2(x+4) + 2 = y+4
2x + 8 + 2 = y+4
2x + 10 = y + 4
2x + 10 - 4 = y
2x + 6 = y ------------ (reduced second equation)
(Law of Subtraction)
3x - 5 = y
- 2x + 6 = y
x -11 = 0
x = 11
So x, the present age of Abel is 11.
Let us find y, the present age of Angela.
3x - 5 = y
3 (11) - 5 = y
33 - 5 = y
28 = y
So y, the present age of Angela is 28.
Question: How old is Angela 5 years ago?
So, y = 28, 28 - 5 = 23
So, Angela's age 5 years ago is 23 years old.
Let x be the present age of Abel, and y be the present age of Angela.
x
y
(Abel and Angela's age 3 years ago)
x-3
y-3
(Angela's age was 1 year more than 3 times Abel's)
3(x-3) + 1 = y-3 -------------------- (First Equation)
(4 years from now, Angela's age will be 2 years more than 2 times the age of Abel)
2(x+4) + 2 = y+4
(Reduce)
3(x-3) + 1 = y-3
3x-9 + 1 = y - 3
3x-9+1+3 = y
3x-5 = y ---------- (reduced first equation)
2(x+4) + 2 = y+4
2x + 8 + 2 = y+4
2x + 10 = y + 4
2x + 10 - 4 = y
2x + 6 = y ------------ (reduced second equation)
(Law of Subtraction)
3x - 5 = y
- 2x + 6 = y
x -11 = 0
x = 11
So x, the present age of Abel is 11.
Let us find y, the present age of Angela.
3x - 5 = y
3 (11) - 5 = y
33 - 5 = y
28 = y
So y, the present age of Angela is 28.
Question: How old is Angela 5 years ago?
So, y = 28, 28 - 5 = 23
So, Angela's age 5 years ago is 23 years old.