[Video] Q18: At what price will the quantity of the product supplied to the market equal the quantity of the product demanded by the market?

Explanation for Question 18 From the Math (Calc) Section on the Official Sat Practice Test 3

Now looking at number 18, we're trying to find the price, 2 right? So we're going to be solving for P where the quantity of the 3 product supplied also known as the SFP, 4 right, is equal to our quantity of the product 5 demanded, which is our DFP. 6 So we essentially want to solve for the price where D of P is 7 equal to SFP. And we need to now create an equation where price 8 is actually variable in it. And so we know that DFP is two 20 9 minus the price. So we can substitute that in for DFP. 10 And we know SFP is one half P plus 40, 11 so we can substitute that in. Um, 12 and then from there we can just simply solve for P right? 13 So add P to both sides so that I get all of my P 14 values on the right hand of the equation. So that's 1.5 P plus 15 40 is equal to two 20, and that also attracts 40 from both sides. 16 So I can get all my normal numbers to the left-hand side of the 17 equation, which gives me 180 is equal to 1.5 P. 18 Now the software P all I need to do is divide by 1.5. 19 And when I do that, these 1.5 will cancel and that'll tell me that 20 120 is equal to P so our best answers, 21 answer, choice B.