3(x+y)-4(x-y)=4
(x+y) of 2+(x-y of 6) =1.
(x+y)/2+(x-y)/6= 1
x/2+x/6+y/2-y/6= 1
2x/3+y/3= 1
2x+y=3 ( 1)
3(x+y)-4(x-y)=4
3x+3y-4x+4y=4
-x+7y=4 (2)
( 1)+2*(2)
y+ 14y= 1 1
y= 1 1/ 15
x=7y-4= 17/ 15
2. Diagonal lines of isosceles trapezoid are perpendicular to each other. If the height of the trapezoid is 5 cm, then the area of the trapezoid is _ 25 _ _.
Because it is an isosceles trapezoid, the diagonal is translated to get an isosceles right triangle. If the height is 5, the length of the hypotenuse is 5X2= 10, that is, upper bottom+lower bottom = 10.
So the area is: 10*5/2=25.