Apr 27, 2017, 13:3104/27/17
X + X + X = 90 -> 3X = 90 -> X = 90/3 -> X = 30.
X - 5Y - 5Y = 20 -> 30 - 10Y = 20 -> 30 - 20 = 10Y -> 10 = 10Y -> Y = 10/10 -> Y=1.
5Y + 4Z = 25 -> 5 + 4Z = 25 -> 4Z = 25 - 5 -> 4Z = 20 -> Z = 20/4 -> Z = 5.
2Z - 1X x 4Y = 10 - 30x4 = 10 - 120 = -110
Result is : - 110, due to observations and order of operations rules.