3a 4b equals 7a 4b

Answer 1

Clearly, there are some signs missing.

So let's try the four possibilities for the second terms:

1. + and +

3a + 4b = 7a + 4b

Subtract 4b from each side: 3a = 7a

Subtract 3a from each side: 0 = 4a

Answer : a = 0, b indeterminate (ie can have any vaue).

2. + and -

3a + 4b = 7a - 4b

Subtract 4b from each side: 3a = 7a - 8b

Subtract 7a from each side: -4a = -8b or 4a = 8b

Answer: a = 2b

3. - and -

3a - 4b = 7a - 4b

Add 4b to each side: 3a = 7a

Subtract 3a from each side: 0 = 4a

Answer : a = 0, b indeterminate (ie can have any vaue).

4. - and +

3a - 4b = 7a + 4b

Add 4b to each side: 3a = 7a + 8b

Subtract 7a from each side: -4a = 8b or 4a = -8b

Answer: a = -2b

Can't do better than that with the information available.