J's answer to gojooo's Primary 6 Maths Algebra Singapore question.
done
{{ upvoteCount }} Upvotes
clear
{{ downvoteCount * -1 }} Downvotes
Tim now: x
Tim in 4 years' time : x + 4
John now: x + 9
John in 4 years' time: x + 9 + 4 = x + 13
Total in 4 years time : x + 4 + x + 13 = 2x + 17
Since total in 4 years' time = 91,
2x + 17 = 91
2x = 91 - 17 = 74
x = 74 ÷ 2 = 37
So Tim is 37 years old now.
Tim in 4 years' time : x + 4
John now: x + 9
John in 4 years' time: x + 9 + 4 = x + 13
Total in 4 years time : x + 4 + x + 13 = 2x + 17
Since total in 4 years' time = 91,
2x + 17 = 91
2x = 91 - 17 = 74
x = 74 ÷ 2 = 37
So Tim is 37 years old now.
Date Posted:
10 months ago
thank you :)
Alternatively,
Sum of ages now = 91 - 4 - 4 = 83
(You have to subtract 4 for each of them)
Sum of ages now also = x + (x + 9)
= 2x + 9
2x + 9 = 83
2x = 83 - 9 = 74
x = 74 ÷ 2 = 37
Sum of ages now = 91 - 4 - 4 = 83
(You have to subtract 4 for each of them)
Sum of ages now also = x + (x + 9)
= 2x + 9
2x + 9 = 83
2x = 83 - 9 = 74
x = 74 ÷ 2 = 37
360 Tutoring Program