First bring all terms in 'a' to the left side of the formula by subtracting ac from both sides
ab - ac - cd = ac - ac
ab - ac - cd = 0
now add cd to both sides
ab - ac -cd + cd = cd
ab - ac = cd
now factor the left side by taking out the 'a'
a(b-c) = cd
now divide both sides by (b-c)
a = cd / (b-c)
done
Quarters equal 25 cents so multiply 25 x32
Answer: 0.31
Step-by-step explanation:
Let A denotes the event that the students report drinking alcohol and B denotes the students report using some type of tobacco product .
Given : P(A) =0.84 ; P(B)=0.33 and P(A∪B)=0.86
We know that 
Then, the probability that the student both drunk alcohol and used tobacco in the past month is given by :-

Hence, the probability that the student both drunk alcohol and used tobacco in the past month = 0.31
90= 3x + 2x
90= 5x
x= 18
one measure = 3(18)= 54
the other one= 2(18)= 36
hope this helps!
He is wrong because he didnt fully simplify the answer, and the answer is $13 per hour