C + c - 14a + 15bm - 13a - 17bm
rearrange
c + c - 14a - 13a + 15bm - 17bm
combine like terms
2c - 27a - 2bm
And got my Math paper 4 IGCSE external tomorrow, thanks for posting this question that helped me more!
The answer of 799/4 is equal 1
The answer is 5:2.
If we take the y-value of 10 and the corresponding x-value of 4, that is 10:4. You can reduce that by diving both numbers by 2. You get 5:2.