He buyed 240 cards because
20
x
12
-----
40
+
20
-------
240
Answer:
its 16
Step-by-step explanation:
First set up a linear equation and using the x and y values in the table see if it solves.
It doesn't solve so we know it isn't linear. ( I won't show all those steps because they aren't needed.)
Using the quadratic formula y = ax^2 +bx +c
Build a set of 3 equations from the table:
C is the Y intercept ( when X is 0), this is shown in the table as 6
Now we have y = ax^2 + bx + 6
-2.4 =4a-2b +6
1.4 = a-b +6
Rewrite the equations
a=b/2 -2.1
1.4 = b/2-2.1 +6
b = 5
a = 5/2 -2.1 = 0.4
replace the letters to get y = 0.4x^2 + 5x +6
Use the website: mathpapa.com/algebra-calculator.html
Answer:
90
Step-by-step explanation:
8*5 = 40
40 + 5 = 45
1/2 x = 45
x = 90
