X = -15 because first u move the ax’s to one side so it would be 3x-5x=25+5 then u calculate each side 3x-5x= -2x and 25+5=30 so -2x=30 and then u divide both sides by -2 and -2/-2 cancels out and 30/-2 equals -15 (I hope his helps) :))
It is given in the question that
Anna buys 12 pens and 20 pencils for a total cost of $16. One pen costs $0.40 more than a pencil.
Let the cost of pencil is $ x .
Therefore cost of pen is

According to the question

Distributing 12 and combining like terms, we will get

Therefore cost of pencil is $0.35 and cost of pen is

Answer: a) 0.84 b) 0.67 c) 1.28
Step-by-step explanation:
Using the standard normal distribution table for z-value , we have
(a) The value of
would result in a 80% one-sided confidence interval : 
(b) The value of
would result in a 85% one-sided confidence interval : 
(c) The value of
would result in a 90% one-sided confidence interval : 