Question 19·Easy·Linear Equations in Two Variables
The equation above relates the variables and . Which equation correctly expresses in terms of ?
For questions that ask which equation "expresses in terms of ," focus on isolating . Perform inverse operations step by step: get the term alone, then divide by its coefficient, and finally simplify any fractions by distributing the division across each term. Pay close attention to signs (positive/negative) and do not accidentally flip fractions—this is where many mistakes with slopes and intercepts occur.
Hints
What does "express in terms of " mean?
Think about how you would rearrange the equation so that is by itself on one side and everything else is on the other side involving only and numbers.
How to undo the multiplication by 3
In the equation , is being multiplied by . What operation can you perform on both sides of the equation to get rid of that ?
Simplify the fraction
After you divide both sides by , you will get a fraction with on top and on the bottom. Try writing this as two separate terms: one involving and one constant term. Be careful with the negative sign.
Desmos Guide
Graph the original equation
In Desmos, type the original equation exactly as given: 4x - 7 = 3y. Desmos will draw the line that represents this relationship between and .
Graph each answer choice
On separate lines, type each answer choice (for example, y = (3/4)x - 7/4, y = (4/3)x + 7/3, etc.). You will now see several lines on the same coordinate plane.
Compare the graphs
Look for the line from the answer choices that lies exactly on top of (coincides with) the graph of 4x - 7 = 3y for all -values. The equation whose graph perfectly overlaps with the original equation’s graph is the correct choice.
Step-by-step Explanation
Understand what the question is asking
"Express in terms of " means you should rewrite the equation so that is alone on one side and everything else is written using on the other side. In other words, you want an equation that looks like .
Isolate the term with
You are given:
.
The term is . To isolate , first notice that is multiplying . To undo this, divide both sides of the equation by :
.
You can also write this as .
Separate the fraction to see the slope and intercept
Now simplify by splitting the numerator into two separate fractions:
.
This makes it clear that the coefficient (slope) in front of is and the constant term (the -intercept) is .
Match your equation to the answer choices
From the simplified form, you have:
.
Compare this with the answer choices and see that it exactly matches choice D, so the correct equation is .