Answer:
Error in the third line.
Step-by-step explanation:
There is an error in the third line.
We are dividing through by 7 but mx is not divided by 7.
Correct solution is:
mx + 7nx =7
x(m + 7n) = 7
x = 7 / (m + 7n).
Remember some simle log rules
loga+logb=log(ab)
xloga=loga^x

means

also, if no base is stated, assume base 10
so
log(2x)=-1 is base 10 and translates to
10^-1=2x
1/10=2x
divide both sides by 2 aka times 1/2
1/20=x
3log(2)+log(x)=3
log(2^3)+log(x)=3
log(8)+log(x)=3
log(8x)=3
base 10
10^3=8x
1000=8x
divide both sides by 8
x=125
Answer:
x = -1/4 = -0.250
Step-by-step explanation: