more math..
posted by True on .
Find the value of x for which the equation below is true.
5x  2y  8
x + 6y = 10
A.16
B.1
C.4
D.1

I do not know if there is a typo, notably on the RHS of the first equation.
I assume the question reads as follows. If not, the same strategy can be used.
5x  2y= 18 ...(1)
x + 6y = 10 ...(2)
The use of absolute value on the righthand side (RHS) of the equality sign is unnecessary, but probably helps to underline the situation.
The two equations can be reduced to the equivalent version:
5x  2y = ±54 ...(1A)
x + 6y = ±10 ...(1B)
Multiply (1A) by 3 and add to (1B):
15x6y+x+6y = ±18±10
16x = ±54±10
so
16x = 64, or 44, or 44, or 64
From which only the first case x=4 appears on one of the choices (C).
If there is no typo, or if the equations are different from (1) and (2), you can use the same solution strategy. 
I do not know if there is a typo, notably on the RHS of the first equation.
I assume the question reads as follows. If not, the same strategy can be used.
5x  2y= 18 ...(1)
x + 6y = 10 ...(2)
The use of absolute value on the righthand side (RHS) of the equality sign is unnecessary, but probably helps to underline the situation.
The two equations can be reduced to the equivalent version:
5x  2y = ±18 ...(1A)
x + 6y = ±10 ...(1B)
Multiply (1A) by 3 and add to (1B):
15x6y+x+6y = ±54±10
16x = ±54±10
so
16x = 64, or 44, or 44, or 64
From which only the first case x=4 appears on one of the choices (C).
If there is no typo, or if the equations are different from (1) and (2), you can use the same solution strategy.