Izzati, Ai Ling, Rina and Susan share some stamps. Izzati and Ai Ling take 1/4 and 1/8 of the total number of stamps respectively. After that, Rina takes 7/10 of the remaining stamps. Eventually, all the remaining stamps are taken by Susan. If Susan gets 42 stamps, find the total number of stamps.​

224 stamps

Step-by-step explanation:

Let total number of stamps = x

1/4 + 1/8 = (2 + 1) /8 = 3/8

3/8 of x = 3x/8

Remaining stamp = x - 3x/8 = (8x-3x)/8 = 5x/8

Rina = 7/10 of 5x /8

Rina = 7/10 * 5x /8 = 35x / 80

Remaining stamps = 5x/8 - 35x/80

Remaining stamps = (50x - 35x)/80 = 15x /80

15x / 80 = 42

15x = 80 * 42

15x = 3360

x = 3360 / 15

x = 224 stamps

if the eqn of the parabola is f(x) = (x-4)(x+2), we need to mult. this out to find the coordinates of the vertex.

then f(x) = x^2 + 2x - 4x - 8, and f(x) = x^2 - 2x - 8.

one way in which you can find the vertex is to calculate x = -b / (2a).   here, that comes to

        )

x = = 1.   f(1) = 1^2 - 2(1) - 8 = - 9.   vertex is at (1, -9).

        2(1) 

find another point on the curve:   let x=0, for which y=-8.   then (0, -8) is on the curve.   plot the vertex and this point and draw a smooth parabola thru both.

hope this