Question

The cost of 7 pen 8 pencils and 3 sharpener his cost 20 and the cost of 3 pencils 4 sharpener and 5 eraser his cost 21 and the cost of 4 pen 4 sharpener and 6 eraser his cost
25 make the equation and solve this

Answer 1

Here is the equation
7x+8y+3z=20
3x+4y+5z=21
4x+4y+6z=25

-x-z=-4
X+z=4

X=4-z
Put in 1st eqn
28-7z+8y+3z=20
8y-4z=20 (2y-z=5)
12-3z+4y+5z=21
4y+z=9

2y-z=5
4y+z=9
=6y=14
Y=14/6
Y=7/3
Put in 2nd
2*7/3-z=5
14/3-5=z
Z=-1/3

X=4-z
X=4-1/3
X=11/3