Please explain to me how to work both these problems. Thank you.

x+x^2/2 +2x^2-x=

and

y^2/4 + y/3 +y^2/3 -y/5= 7y^2/12 + 2y/15

x+x^2/2 +2x^2-x=

collect like terms, those with x and those with x^2
x - x + (1/2)x^2 + 2 x^2
0 + (1/2 + 2/2) x^2
(3/2) x^2

and

y^2/4 + y/3 +y^2/3 -y/5= 7y^2/12 + 2y/15

(1/3 -1/5) y + (1/4 +1/3) y^2 =(7/12)y^2 + (2/15)y

(5/15 - 3/15) y + (3/12 + 4/12) y^2 = (7/12)y^2 + (2/15)y

(2/15) y + (7/12) y^2 =(7/12)y^2 +(2/15)y
sure enough