It needs more information for someone to answer sorry:/
If you would like to solve a set of equations, you can do this using the following steps:
equation a: y = 15 - 2z /*(-2)
equation b: 2y = 3 - 4z
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-2y = (-2) * (15 - 2z)
-2y = -30 + 4z
2y = 3 - 4z
The mistake was made at step 2: −2y = 15 − 2z [equation a in step 1 is simplified.]. The correct simplification would be <span>-2y = -30 + 4z. </span>
3x-8 = 8x-33
3x-8x = -33+8
-5x = -25
x = -25/-5
x = 5