Do the math the same way you would if all the other variables were numbers. For linear equations such as these, you can
• subtract one side of the equation, so you get an equation equal to zero.
• factor out the variable of interest
• subtract all terms that don't have the variable as a factor
• divide by the coefficient of the variable.
19. 2xy - x - 7 = 0 . . . . subract the right side
x(2y-1) -7 = 0 . . . . factor out x
x(2y -1) = 7 . . . . subtract the term(s) not containing x. Subtract -7 here.
x = 7/(2y -1) . . . . divide by the coefficient of x
20. Usually for these, you would eliminate fractions first. (You don't have to, but it does simplify things a bit.)
2d + f = 24 . . . . multiply the equation by 4 to eliminate fractions
f = 24 - 2d . . . . subtract the term not involving f
21. We can go back to the above sequence of steps here, if you like.
3(2j -k) -108 = 0 . . . . subtract the right side
6j -3k -108 = 0 . . . . separate the j terms from the others (eliminate parentheses using the distributive property)
6j = 108 + 3k . . . . add the opposite of the non-j terms
j = 108/6 + 3k/6 . . . . divide by the coefficient of j
j = 18 + k/2 . . . . simplify
22. "solve for" variable not specified.
t = (3.5s -42)/4
s = (4t+42)/3.5
In both cases, the 3.5 can be replaced by 7/2 and the fraction simplified.
t = (7/8)(s-12)
s = 12 + (8/7)t
Answer:
18 days
Step-by-step explanation:
Let x represent number of days.
We have been given that Brandy's watch falls 1 second every day. So Brandy's watch will fall 
seconds behind in x days.
We are also told that Brandy set her watch 4 seconds behind, so Brady's watch will be behind by total 
seconds in x days.
Since Brady's watch is 22 seconds behind, so we will equate by 22 to solve for x as:
Therefore, Brandy set her watch 18 days ago.
Step-by-step explanation:
25 - 2(5 + 4x)
= 25 - 10 - 8x (Distributive Property)
= 15 - 8x.
Substitute y = 2x - 15 to the second equation:
4x + 3(2x - 15) = -5 use distributive property
4x + (3)(2x) + (3)(-15) = -5
4x + 6x - 45 = -5 add 45 to both sides
10x = 40 divide both sides by 10
x = 4
Substitute the value of x to the equation y = 2x - 15:
y = 2(4) - 15 = 8 - 15 = -7
<h3>Answer: (4, -7)</h3>
subtract 4x from both sides and you get y=4x
y varies directly with x. When x is 1, y is 1/4. when x is 4, y is 1. when x is 8, y is 2. So on and so on. Sorry if this is confusing. Direct variations is one of my weak points
