Verified answer

Probably 8

The best clue is the denominators. What multiple of 17 is sixty-something? That'd be 68. Let's test

48 / 68 + 5/17 =>

12/17 + 5/17 =>

17/17

If you subtract 5/17 from both sides of the equation 4Δ/6Δ + 5/17 = 1, you get:

4Δ/6Δ = 12/17

You could at this point try 0 through 9 for the possible digits represented by Δ. If you wanted to do it algebraically, I'd prefer to call it X if you don't mind. The two digit number 4X means 40 + X, right? And the two digit number 6X means 60 + X. So that proportion really is:

(40+X) / (60+X) = 12/17

Cross multiply

17(40+X) = 12(60+X)

680 + 17X = 720 + 12X

5X = 40

X = 8

Therefore, Δ is 8

48/68 when this is divided by 4 you get 12/17

You had the question all figured out. If you have no other method what you could do is just try the digits from 1 to 9 to see what happens. For example try 3

43/63. 43 is a prime number. So that is the wrong number: it will not reduce to 12/17.

If you are in higher standard you can use Kathleen K answer

for lower standards

4Δ ....1....5

----- = -- – -----

6Δ ,,,,1 .. 17

=

4Δ ....12

----- = ----

6Δ ,,,, 17

find multiple of 12 and 17 having 8 in unit plaxe.

12 × 4 = 48 and 17 × 4 = 68

=

48 ....12

----- = ----

68 ,,,, 17

=

Δ = 8

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