Maths help me

y+2/5-3(y-3)/10=1/4

全部sol：
y+2/5-3(y-3)/10=1/4
y-(3y-9)/10=1/4-2/5
10y/10-(3y-9)/10=5/20-8/20
(7y+9)/10=-3/20
7y+9=-3/20 x 10
7y+9=-3/2
7y=-3/2-9
7y=-3/2-18/2
7y=-21/2
y=-21/14
y=-3/2

簡單D：
y+2/5-3(y-3)/10=1/4
10y/10-(3y-9)/10=5/20-8/20
(7y+9)/10=-3/20
7y+9=-3/2
7y=-21/2
y=-3/2

努力點讀書就可以明白當中技巧的啦~
還有選我啊，很多人都等第一個回答然後照copy架~~

y+2/5-3(y-3)/10=1/4

y+2/5-(3y-9)/10=1/4

y=1/4-2/5+(3y-9)/10

y=5/20-8/20+(6y-18)/20

y=(6y-21)/20

20y=6y-21

20y-6y=6y-6y-21

14y= -21

14y/14= -21/14

y= -3/2

y= -1.5