Do you mean:
5x + 9 - 7x + 6 = x - 18
If so, you can solve this question at this manner:
-2x + 15 = x - 18
3x = -3
x = -1
18
18.
6 - -12 = 18
18 + 12 + 0 - 4 - 10 = 16
10x3+8=80-60+? 30+8=20+? 38=20+? 38-20=? 18=? The answer is 18.
18
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When subtracting a negative number, you can think of it as adding the positive equivalent. In this case, 18 minus a negative 18 is the same as 18 plus 18, which equals 36. This is because subtracting a negative number is equivalent to adding its positive counterpart.
Negative 23 + 32 minus 18 = negative 9 {-23+32-18=-9)
Oh, dude, if 5 plus n equals 23, then n must be 18, right? So, if you wanna find out what n minus 5 equals, just subtract 5 from 18 and you get 13. Easy peasy lemon squeezy.
18.
6 - -12 = 18
-18
18 + 12 + 0 - 4 - 10 = 16
10x3+8=80-60+? 30+8=20+? 38=20+? 38-20=? 18=? The answer is 18.
72 but there is such a thing as a CALCULATOR
If you mean 3y+24 = y-12 then the value of y works out as -18